Tag: physics

Questions Related to physics

The smallest magnet available is ___________.

properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics neutral points magnetic poles and magnetic compass

  1. a bar magnet with an area of $1 mm^2$

  2. a spinning electron

  3. a magnetic dipole

  4. a molecule or atom with a magnetic dipole

Show answer
Correct Option: B
Explanation:

An electron is not a spinning ball of charge and the intrinsic spin of particles cannot be understood in such terms. a value of the ratio between the magnetic moment and the angular momentum that is a factor 2 too small.

The smallest magnet available is a spining electron.

The magnetic domains of an unmagnetised object are found ___________.

properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics neutral points magnetic poles and magnetic compass

  1. Parallel to each other

  2. Perpendicular to each other

  3. Pointing towards south

  4. Pointing in different direction

Show answer
Correct Option: D
Explanation:

A magnetic domain is the region in which the magnetic fields of atoms are grouped together and aligned. In an unmagnetized object the magnetic domains are pointing at different directions.

The primary origin of magnetism lies in the

properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics neutral points magnetic poles and magnetic compass

  1. atomic current and intrinsic spin of electrons.

  2. polar and non polar nature of molecules.

  3. pauli exclusion principle.

  4. electronegative nature of materials

Show answer
Correct Option: A
Explanation:

Atomic currents and intrinsic spins of electrons are responsible for origin of magnetism.

If we go inside a mine and drop a $104 lb$  iron ball and $1$ lb aluminum ball from the top of a high platform, neglecting air resistance.

properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics neutral points magnetic poles and magnetic compass

  1. Both will reach the floor at the same time

  2. $1$ lb weight will reach the floor first

  3. $10$ lb weight will reach the floor first

  4. It is not possible to indicate which of the two will reach the floor first without further data

Show answer
Correct Option: A
Explanation:
In real life the one having less volume and more weight will reach first

but in ideal situation where viscosity of air is neglected both will hit ground at same time irrespective of their masses if dropped from the same height 

this is because the acceleration produced due to gravity does not depend on the body.


Point out the right statements about the validity of Kirchhoff's junction rule.

physics kirchhoff's law circuit problems kirchoff's law and problems on it equivalent resistance in series and parallel connection

  1. It is based on conservation of charge

  2. Outgoing currents add up and are equal to incoming currents at a junction

  3. Bending or reorienting the wire does not change the validity of Kirchhoff's junction rule

  4. All of above

Show answer
Correct Option: D
Explanation:

By Kirchhoff's junction rule. Incoming current $=$ Outgoing current

The net charge is conserved and it is based on conservation of charge.
Also bending or reorienting the wire does not invalidate the conservation of charge principle. So, option D is correct.

Kirchoff's junction law is equivalent to ___________.

physics kirchhoff's law circuit problems kirchoff's law and problems on it equivalent resistance in series and parallel connection

  1. Conservation of energy

  2. Conservation of charge

  3. Conservation of electric potential

  4. Conservation of electric flux

Show answer
Correct Option: B
Explanation:

Kirchhoff's junction rule is an application of the principle of conservation of electric charge: current is flow of charge per time, and if current is constant, that which flows into a point in a circuit must equal that which flows out of it. 

Kirchoffs law of junctions is also called the law of conservation of:

physics kirchhoff's law circuit problems kirchoff's law and problems on it equivalent resistance in series and parallel connection

  1. Energy

  2. Charge

  3. Momentum

  4. Angular momentum

Show answer
Correct Option: B
Explanation:

Kirchoff's second law:- According to the law, at a particular junction the charge entering the junction is equal to charge exiting that junction.
$ \Rightarrow$ There is no charge accumulated at junction. This is also called as law of conservation of charge.

Consider the following two statements:
(A) Kirchhoff's Junction Law follows from conservation of charge.
(B) Kirchhoff's Loop Law follows from conservative nature of electric field.

physics kirchhoff's law circuit problems kirchoff's law and problems on it equivalent resistance in series and parallel connection

  1. Both A and B are correct

  2. A is correct but B is wrong

  3. A is correct but A is wrong

  4. Both A and B are wrong

Show answer
Correct Option: A
Explanation:

Kirchhoff's Junction law states that total current(charge) entering the junction is equal to total current(charge) leaving the junction hence, total charge across junction remains conserved.
Also, Kirchhoff's loop law states that the directed sum of the electrical potential differences (voltage) around any closed network is zero or the sum of the emfs in any closed loop is equivalent to the sum of the potential drops in that loop. 

Kirchoff's first law, i.e., $\sum    i = 0$ at a junction, deals with the conservation of

physics kirchhoff's law circuit problems kirchoff's law and problems on it equivalent resistance in series and parallel connection

  1. charge

  2. energy

  3. momentum

  4. angular momentum

Show answer
Correct Option: A
Explanation:

The principle of conservation of electric charge implies that: at any node (junction) in an electrical circuit , the sum of currents flowing into that node is equal to the sum of currents flowing out of that node. This is known as Kirchhoff's current law.

Consider the following two statements:
1) Kirchoff's junction law follows from the conservation of charge
2) Kirchoff's loop law follows from the conservation of energy. 
Which of the following is correct?

physics kirchhoff's law circuit problems kirchoff's law and problems on it equivalent resistance in series and parallel connection

  1. both 1 and 2 are wrong

  2. 1 is correct and 2 is wrong

  3. 1 is wrong and 2 is correct

  4. both 1 and 2 are correct

Show answer
Correct Option: D
Explanation:

Kirchhoff's loop law follows conservation of energy, nature of electric field.

Kirchhoff's junction law follows from the conservation of charge.