# NCERT Solutions for Class 12 Physics

NCERT Exemplar Problems Class 12 Physics Solutions Pdf free download was designed by expert teachers from the latest edition of NCERT Exemplar Books to get good marks in board exams. Here we have given CBSE NCERT Exemplar Problems with Solutions for Class 12 Physics.

## FAQ – NCERT Solutions for Class 12 Physics

### What’s Ohm’s Law?

Ohm’s law states the relationship between potential difference and electric current. A current that flows via a conductor is directly proportional to an applied voltage. Moreover, it offered which all physical states & temperatures requires to remain constant. This is significant the reason in other parts when an electric current is passed it increase the temperature. Classic Ohm’s Law violation example is light bulb’s filament.
Ohm’s Law Equation is
V= IR
Where,
V is the voltage across the conductor.
I am the current passing via the conductor.
R is the resistance provided by a conductor inflow of current.

### List down the Factors which affect resistivity?

Electric resistance assesses the amount of restriction offered in the flow of electric charge in the circuit. Below are some of the factors that affect electric resistance.
Conducting device cross-sectional area
The temperature of a conducting material
Conducting device length
Material of conducting device
The electrical resistivity is directly proportional to a length of a conducting device plus inversely proportional to a cross-sectional area of a conductor.
R = pL/A
p is the material resistivity which is measured in ohm-meter

### State Kirchhoff’s Law?

Kirchhoff’s 1st Law (Current-Law)
According to Kirchhoff1st Law, the total current getting in the junction or node is the same as the charge which leaves the junction or node, as no charge will be lost. This explains the algebraic sum of all the current getting in & getting out of the node is the same as zero.

Kirchoff’s 2nd Law (Voltage-Law)
The 2nd Law of Kirchhoff states that the sum of the entire voltage drop is the same as voltage around a loop in a similar loop for a closed network & also the same as zero. The algebraic sum of all voltage in a loop should be zero & it’s known as energy conservation.

### Explain the 2 kinds of Resistance?

There are essentially 2 major kinds of resistors. They include resistors in parallel & resistors in series. In a case with resistors in parallel, the variation among all resistors remains similar. Moreover, the difference is the same as the applied difference. When resistors are in a series similar amount of current flows via every resistor when there’s any change.

### Is it necessary to utilize satellites for TV transmission at long distances? Why?

Television signals aren’t reflected by the ionosphere atmosphere layer, TV broadcasts from air earth stations need to be reflected on the ground through an artificial satellite.

### Explain magnetic dipole?

A magnetic dipole is referred to as a pair of the same magnitude of pole-strength though opposite poles nature separated via a small-distance “2l”.
Magnetic moment Mathematical Equation
M = m * 2l
“Ampere metre-square” is an SI-unit of the magnetic moment
This is a kind of vector quantity
Magnetic direction moment is from North-South.
When the current direction is clockwise then the magnetic moment direction is inwards. When the current direction is anti-clockwise then the magnetic moment direction is outwards.

X-rays
Red light
Microwaves

### How do beam frequencies of ultraviolet-light vary, when it moves from air to glass?

We understand that frequency of UV-light is unaffected by the frequency of ultraviolet light beam change & when it moves from air to glass.

### What’s the purpose of the ozone layer in the atmosphere?

The major role of the ozone layer in the atmosphere is it absorbs every harmful UV rays & protects us from detrimental effects.

### List some of the uses of Infrared radiations?

Infrared radiations are used to uncover old walls’ secret-writings Photographs taken at foggy situations are taken with the help of infrared radiation

### Skywaves aren’t utilized in transmitting signals for TV, Explain? Explain two methods in which the range of TV transmission is increased?

Skywaves aren’t transmitting TV-signal, the reason being the ionosphere doesn’t reflect sky waves, and they’re not utilized for broadcast TV signals.
Ways of increasing TV transmission range
Geostationary satellites
Tall antenna

### Explain what is meant by the term electromagnetic waves?

Waves that are radiated through an accelerated variation propagating via space as combined as magnetic & electric fields that oscillate perpendicular to every other & to the direction of propagation that’s known as electromagnetic-waves. Electromagnetic waves can also state as disturbances made by both magnetic & electric fields that are equally perpendicular to every other. A magnetic field that’s a time variable is a source of a varying electric field. And also, a changing-magnetic field that’s produced from one time-varying electric field. #### Robin Singh

Robin Singh is education professional tutor of NCERT. I have good knowledge of CBSE all subjects. Expert in maths, physics and chemistry. if students have any doubt about NCERT Solutions so contact us info@cbsenotes.in.

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