Tag: physics

Questions Related to physics

The force acting on a pole of strength of 20 Am is 8x10$^{-4}$ N, when placed in a magnetic field. The magnetic induction field strength is :

electrostatic and magnetic analogy magnetism and matter magnetic effects of current and magnetism physics

  1. 4$\times $10$^{-6}$ T

  2. 0.4$\times $10$^{4}$ T

  3. 4 G

  4. 4$\times $10$^{-5}$ T

Show answer
Correct Option: D
Explanation:

$m=20Am$
$F=8\times10^{-4}N$
$F=Bm$
$8\times 10^{-4}=20\times B$
$B=4\times 10^{-5}T$

Two magnetic poles have their strengths in the ratio 3 : 2. They are kept at a distance of 0.6 m in air and the force of repulsion is found to be 0.06 dynes. The pole strengths are (in amp. m)

electrostatic and magnetic analogy magnetism and matter magnetic effects of current and magnetism physics

  1. 1.8, 1.2

  2. 18, 12

  3. 6, 4

  4. 0.6, 3.6

Show answer
Correct Option: A
Explanation:

$1 dyne = 10^{-5}$
$\mu _{0}=4\pi \times 10^{-7}TmA^{-1}$ 
$m _{1}=3m$
$m _{2}=3m$
$F=\dfrac{\mu _{0}m _{1}\times m _{2}}{4\pi \times r^{2}}$ r=0.6m
$0.06\times 10^{-5}=\dfrac{4\pi \times 10^{-7}\times 3m\times 2m}{4\pi \times (0.6)^{2}}$
$m^{2}=(0.6)^{2}$
$m=0.6$
$m _{1}=1.8$
$m _{2}=1.2$




Wires used in homes are usually covered with materials like plastic or rubber. This is done to

physics effects of electric current precaution with the electrical circuit precautions to be taken while dealing with current devices used to protect from shock of electric current

  1. Prevent rusting

  2. Make handling easier

  3. Prevent shocks & short circuits

  4. Make them look beautiful

Show answer
Correct Option: C
Explanation:

Insulators are used in electrical equipment to support and separate electrical conductors without allowing current through themselves.

therefore it prevent us from shocks and short circuits.

Find odd man out.
Dry cell, Solar cell, Generator, Electric bulbs.

physics effects of electric current precaution with the electrical circuit precautions to be taken while dealing with current devices used to protect from shock of electric current

  1. Generator

  2. Solar Cell

  3. Dry Cell

  4. Electric bulbs

Show answer
Correct Option: D
Explanation:

It is an electrical appliance, rest are sources of electricity.

State whether given statement is True or False
Earth connection saves the user from electric shocks.

physics effects of electric current precaution with the electrical circuit precautions to be taken while dealing with current devices used to protect from shock of electric current

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

The current takes the path that is having less resistance . Hence lesser the resistance higher the current and higher the resistance lower the current. So in case of shock current passes though you. A normal person have a resistance of about $10\times 10^3\Omega $ and as there is no different path for the current to move hence its passes to ground though you.  

but in case a earth connection the current have almost no resistance path through the ground wire to the ground.
Therefore it helps in saving the user from electric shocks. 

All wires used in electric circuits should be covered with

physics effects of electric current precaution with the electrical circuit precautions to be taken while dealing with current devices used to protect from shock of electric current

  1. a coloured material

  2. an insulating material

  3. a conducting material

  4. none of these

Show answer
Correct Option: B
Explanation:

he most important reason why electrical wires are covered in insulating material is to protect people from electrical shock, and  protection from short circuit.

State whether given statement is True or False
All electrical appliances should be properly earthed.

physics effects of electric current precaution with the electrical circuit precautions to be taken while dealing with current devices used to protect from shock of electric current

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

All electrical appliances should be properly earthed because to prevent us from shock. This statement is true.

State whether given statement is True or False.
We must not touch electric switches with bare hands.

physics effects of electric current precaution with the electrical circuit precautions to be taken while dealing with current devices used to protect from shock of electric current

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

It is not in general sense, but for protection purpose from any kind of defect in the insulator material damage in the electrical switch we must not touch it withh bare hands specially in case our hands are wet.

Find odd man out.
Water heater, Electric kettle, Electric iron, Electric fuse

physics effects of electric current precaution with the electrical circuit precautions to be taken while dealing with current devices used to protect from shock of electric current

  1. Water Heater

  2. Electric kettle

  3. Electric fuse

  4. Electric Iron

Show answer
Correct Option: C
Explanation:

It is a safety device, rest are electrical appliances.

A person may get a severe electric shock on touching a :

physics effects of electric current precaution with the electrical circuit precautions to be taken while dealing with current devices used to protect from shock of electric current

  1. a neutral wire

  2. a live wire

  3. an earth wire

  4. none of these

Show answer
Correct Option: B
Explanation:

A person may get a severe electric shock on touching the live wire. Because live wires have high potential and current flows through our body (low potential ). Thus we get electric shocks.