Define Physics?
Physics is the branch of science concerned with the nature and properties of matter and energy.
The subject matter of physics includes mechanics, heat, light and other radiation, sound, electricity, magnetism, and the structure of atoms.
What is Slide Wire Bridge?
It is a practical form of Wheatstone bridge and used to find unknown resistance of a wire.
Define specific resistance or resistivity?
The resistance of a material having unit length and cross sectional area is called specific resistance or resistivity. Its SI unit’s W-m.
Define Conductivity and write its units?
Reciprocal of resistivity is called conductivity and its SI units W-m-1.
What is eureka wire?
It is an alloy of 40% nickel and 60% copper.
What is principal of Slide Wire Bridge?
The principal of slide wire bridge is R1/R2=R3/R4
Why Galvanometer is shunted?
When galvanometer is shunted, current comes into limit.
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What is Galvanometer?
The electrical instrument used to detect current in a circuit is called galvanometer.
What is Resistance of Galvanometer?
The resistance of coil of a galvanometer is called resistance of galvanometer.
What is Shunt Resistance?
The small resistance connected in parallel to galvanometer to provide alternative current path so that deflection comes into scale is called shunt resistance.
Why Galvanometer shows half deflection?
Galvanometer shows deflection because current is divided into two paths. Half current flows through galvanometer and half current through shunt resistance.
Names the main parts of galvanometer.
The main parts of galvanometer are coil, permanent magnet, and deflection measuring scale along pointer.
What is the sensitivity of Galvanometer?
Current through galvanometer is given as I=Cq/NAB. When C/NAB is small, galvanometer is called sensitivity of galvanometer.
What is the stability of Galvanometer?
Current through galvanometer is given as I=Cq/NAB. When C/NAB is large, galvanometer is called stable
What is full scale current on Galvanometer?
The full scale current on galvanometer is Ig = E x n /(r + Rg)q
How many keys are used in experiment to determine the resistance of Galvanometer by half deflection method?
Two keys are used in this experiment.
Are galvanometer, battery, HRB, and key K1 are connected in series or parallel in half deflection experiments?
Yes, galvanometer, battery, HRB, and Key are connected in series in half deflection experiments.
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What is Ammeter?
The electrical instrument used to measured current in a circuit is called ammeter.
How Ammeter is connected in a circuit?
Ammeter is always connected in series in a circuit to measure current.
How Galvanometer is converted into Ammeter?
When shunt resistance is connected in parallel to galvanometer, the galvanometer becomes ammeter.
What is difference between Galvanometer into Ammeter?
The ammeter is used to measure current while galvanometer is used to detect current.
Why Ammeter is low resistance device?
The low resistance of ammeter does not decrease the current of actual circuit.
What is figure of merit?
The value of current for one division of galvanometer is called figure of meter.
What is multi Ammeter?
The ammeter having many ranges and can be adjusted with a knob is called multi ammeter.
What is least count of Ammeter?
The smallest reading on scale of ammeter is called its least count.
Why Ammeter is always connected in series to measure current?
In series resistances current has single way to flow. It means current flowing through circuit element also passes through ammeter.
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What is Voltmeter?
The electrical instrument used to measured voltage in a circuit is called voltmeter.
How Voltmeter is connected in a circuit?
Voltmeter is always connected in parallel in a circuit to measure voltage.
How Galvanometer is converted into Voltmeter?
When high resistance is connected in series to galvanometer, the galvanometer becomes voltmeter.
What is least count of voltmeter?
The smallest reading on scale of voltmeter is called its least count.
Why voltmeter is high resistance device?
The maximum voltage is dropped across high resistance of voltmeter. It is always connected in parallel to circuit elements so that accurate voltage is measured.
How does pd very across resistance in series?
Pd varies according to value of resistance. Pd across a resistance is high for high resistance. Pd is directly proportional to resistance.
What is AVO meter?
AVO meter means Ammeter, Voltmeter and Ohmmeter. It is used to measure current, voltage and resistance.
What is Multi Voltmeter?
The voltmeter having many ranges and can be adjusted with a knob is called multimeter.
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What is potentiometer?
The instrument used to measure potential difference or to compare pd is called potentiometer.
What is internal resistance of a cell, write its units.
The operation to flow of charges due to electrolyte of cell is called internal resistance of cell. Its units are ohm.
What is battery or storage cell?
The device which converts chemical energy into electrical energy is battery or storage cell.
Does internal resistance of a cell remain constant?
The internal resistance of a cell decreases with increase in current.
What is formula “To determine internal resistance of a cell using potentiometer”?
The formula used to this experiment is r = (L1-L2) R / L2
What is principal of potentiometer?
The pd is directly proportional to length of wire is the principal of potentiometer.
What is emf of a cell?
The amount of work done on unit positive charge by cell to shift charge from low potential to high potential is called emf of cell.
What is unit of emf?
The unit of emf is volt. One joule work done on 1C charge is called one volt.
Why the weak current should is used in potentiometer wire?
The weak currents are used in potentiometer wire so that small heat dissipation takes place and resistance of wire does not charge due to heat.
When terminal potential is equal to emf of cell?
Terminal potential and emf if a cell are related as e = I r + Vt current is zero, when r = 0 when R = ¥ (open circuit). In this case e = Vt
What does one sided deflection of galvanometer indicates in experiment of emf of a cell by potentiometer?
The emf of a battery used is less than emf of cell whose emf is to be determined.
If two equal resistances are connected across a battery, how pd vary?
Both pd and current through each resistance is same.
White formula to find emf of a cell?
Formula of emf of a cell is ex = V L1/L
Write formula to compared emf of two cells?
Formula to compare emf of two cells is e1/e2 =L1/L2
Name some sources of emf?
The names of some sources of emf are dry cell, solar cell, generator, and thermocouple.
Under What conditions terminal potential is greater then emf of a cell?
The terminal potential is greater then emf of a cell when battery is being charged.
What is difference between terminal potential and emf of a cell?
The potential difference across external resistance is called terminal potential. It is related with emf of a battery as e= I r + Vt
Why deflection on galvanometer is zero at balance point in experiment emf of a cell?
When emf of a cell becomes equal to pd across two points of wire, the galvanometer shows deflection.
How can you increase sensitivity of potentiometer?
The sensitivity of potentiometer can be increased by increasing balance length of wire.
What is ohm’s law?
The pd across ends of a conductor is proportional to current provided that physical state of conductor remains constant which is temperature.
Does tungsten filament bulb obey ohm’s law?
Tungsten filament bulb does not obey ohm’s law because physical state called temperature is not constant.
What is shape of graph between V and I for tungsten filament bulb?
The graph between V and I for tungsten filament bulb is exponential increasing function.
Why resistances of tungsten filament increases with increase pd?
The resistance of tungsten filament bulb increases with increase in pd because temperature increase.
Are tungsten filament bulb, voltmeter, ammeter, battery, rheostat, and key are connected series?
Tungsten filament bulb, ammeter, battery, rheostat, and key are in series but voltmeter in parallel to bulb.
Scientifically, temperature is a physical quantity which describes how quickly molecules are moving inside a material. In solids and liquids the molecules are vibrating around a fixed point in the substance, but in gases they are in free flight and bouncing off each other as they travel. In a gas the temperature, pressure and volume of the gas are closely related by a law of physics.
An electric current is a flow of electric charge.
The SI unit of electric current is the ampere (A). This is equal to one coulomb of charge in one second. Current can be found in wires, batteries, and lightning.
Resonance is a phenomenon that occurs when a vibrating system or external force drives another system to oscillate with greater amplitude at a specific preferential frequency.
What is ohm’s law?
The pd across ends of a conductor is proportional to current provided that physical state of conductor remains constant which is temperature.
Does tungsten filament bulb obey ohm’s law?
Tungsten filament bulb does not obey ohm’s law because physical state called temperature is not constant.
What is shape of graph between V and I for tungsten filament bulb?
The graph between V and I for tungsten filament bulb is exponential increasing function.
Why resistances of tungsten filament increases with increase pd?
The resistance of tungsten filament bulb increases with increase in pd because temperature increase.
Are tungsten filament bulb, voltmeter, ammeter, battery, rheostat, and key are connected series?
Tungsten filament bulb, ammeter, battery, rheostat, and key are in series but voltmeter in parallel to bulb.
Physical quantity is a quantity in physics that can be measured. Or a physical quantity is a physical property that can be quantified. Examples of physical quantities are mass, amount of substance, length, time, temperature, electric current, light intensity, force, velocity, density, and many others. A physical quantity is always measured of natural non-living objects.
The mass of an object is a measure of an object's resistance to acceleration, sometimes also called "inertia". A mountain has typically more mass than a rock, for instance. Mass should not be confused with the related but quite different concept of weight. A large mass like the Earth will attract a small mass like a human being with enough force to keep the human being from floating away. "Mass attraction" is another word for gravity.
Acceleration is a measure of how fast velocity changes. Acceleration is the change of velocity divided by the change of time. Acceleration is a vector, and therefore includes both a size and a direction.
Measuring
- A line has one size measurement. This one measurement is the length.
- A circle's length is called its circumference.
- A rectangle has two measurements that show its size. These two measurements are the length and the width of the rectangle.
- The length and width of a square are the same.
- Length is also a property of time. An amount of time has a length.
Time We use time to sequence events, to compare their durations and the intervals between them, and to quantify the speed at which objects move and things change.
Units of time
- 1 millennium = 1000 years
- 1 century = 100 years
- 1 decade = 10 years
- 1 lustrum = 5 years
- 1 year = 12 months ≈ 365 days (366 days in leap years)
- 1 month ≈ 28 to 31 days ≈ 4 weeks
- 1 fortnight = 14 days = 2 weeks
- 1 week = 7 days
- 1 day = 24 hours
- 1 hour = 60 minutes
- 1 minute = 60 seconds
- 1 second = SI base unit of time
- 1 millisecond = 1/1,000 second
- 1 microsecond = 1/1,000,000 second
- 1 nanosecond = 1/1,000,000,000 second
- 1 picoseconds = 1/1,000,000,000,000 of a second
- 1 femtosecond = 1/1,000,000,000,000,000 of a second
- 1 attosecond = 1/1,000,000,000,000,000,000 of a second
- 1 Planck time = smallest measurable unit of time
Scientifically, temperature is a physical quantity which describes how quickly molecules are moving inside a material. In solids and liquids the molecules are vibrating around a fixed point in the substance, but in gases they are in free flight and bouncing off each other as they travel. In a gas the temperature, pressure and volume of the gas are closely related by a law of physics.
Temperature and heat
Temperature is not the same as heat. Heat is energy which moves from one thing, cooling it, to another, heating it. Temperature is a measure of the movements (vibration) of the molecules inside a thing. If the thing has a high temperature, it means the average speed of its molecules is fast. A thing may have a high temperature but because it contains very few or light atoms it has very little heat.Heat capacity
The amount of heat that is needed to make a substance one degree higher is called its heat capacity. Different substances have different heat capacities. For example, a kilogram of water has more heat capacity than a kilogram of steel. This means that more energy is needed to make the temperature of water 1 °C hotter than is needed to make the temperature of steel 1 °C hotter.Weather
Temperature is also important in weather and climate. It is related to the amount of heat energy in the air. Isotherm maps are used to show how temperature is different across an area. Temperature will be different during different times of day, different seasons and in different places. It is affected by how much heat reaches the place from the suns rays (insulation), how high the place is above the level of the sea, and how much heat is brought to the place by the movement of winds and ocean currents.Electric current
Electromagnets
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The SI unit of electric current is the ampere (A). This is equal to one coulomb of charge in one second. Current can be found in wires, batteries, and lightning.
Meld's experiment is a scientific experiment carried out in 1859 by the German physicist Franz Meld’s on the standing waves produced in a tense cable.
A model of Meld’s experiment: an electric vibrator connected to a cable drives a pulley that suspends a mass that causes tension in the cable.
The aim of this experiment is to investigate the standing waves on a stretched elastic cord. It forms the basis of all musical notes
Meld’s experiment is a scientific experiment carried out in 1859 by the German physicist Franz Meld’s on the standing waves produced in a tense cable originally set oscillating by a tuning fork, later improved with connection to an electric vibrator. This experiment attempted to demonstrate that mechanical waves undergo interference phenomena. In the experiment, mechanical waves traveled in opposite directions form immobile points, called nodes. These waves were called standing waves by Meld’s since the position of the nodes and loops (points where the cord vibrated) stayed static.
A node is a point along a standing wave where the wave has minimum amplitude. For instance, in a vibrating guitar string, the ends of the string are nodes. By changing the position of the end node through frets, the guitarist changes the effective length of the vibrating string and thereby the note played.
The opposite of a node is an anti-node, a point where the amplitude of the standing wave is a maximum. These occur midway between the nodes
Standing wave – also known as a stationary wave – is a wave in a medium in which each point on the axis of the wave has an associated constant amplitude. The locations at which the amplitude is minimum are called nodes, and the locations where the amplitude is maximum are called antinodes.
The amplitude of a periodic variable is a measure of its change over a single period (such as time or spatial period). There are various definitions of amplitude (see below), which are all functions of the magnitude of the difference between the variable's extreme values. In older texts the phase is sometimes called the amplitude.
Frequency is the number of occurrences of a repeating event per unit time.
Damping is an influence within or upon an oscillatory system that has the effect of reducing, restricting or preventing its oscillations. In physical systems, damping is produced by processes that dissipate the energy stored in the oscillation. Examples include viscous drag in mechanical systems, resistance in electronic oscillators, and absorption and scattering of light in optical oscillators. Damping not based on energy loss can be important in other oscillating systems such as those that occur in biological systems.Resonance is a phenomenon that occurs when a vibrating system or external force drives another system to oscillate with greater amplitude at a specific preferential frequency.
Increase of amplitude as damping decreases and frequency approaches resonant frequency of a driven damped simple harmonic oscillator.
Frequencies at which the response amplitude is a relative maximum are known as the system's resonant frequencies, or resonance frequencies. At resonant frequencies, small periodic driving forces have the ability to produce large amplitude oscillations. This is because the system stores vibrational energy.
Resonance occurs when a system is able to store and easily transfer energy between two or more different storage modes (such as kinetic energy and potential energy in the case of a pendulum). However, there are some losses from cycle to cycle, called damping. When damping is small, the resonant frequency is approximately equal to the natural frequency of the system, which is a frequency of unforced vibrations. Some systems have multiple, distinct, resonant frequencies.
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