Electricity & Magnetism MCQs with Answers

The force between two charges is 28 N in vacuum. If paraffin wax of relative permittivity 2.8 is introduced between the charges as a medium, then the force reduces to _?

• A.7 N
• B.14 N
• C.10 N
• D.20 N

A point lies 3m from a +5μC charge and 4m from a -3μC charge. The most appropriate direction of the net electric field at this point is directed _?

• A.Away from the -3μC charge
• B.Towards the -3μC charge
• C.Towards the +5μC charge
• D.Away from +5μC charge

A rheostat can be used as a _?

• A.Variable resistor
• B.Potential divider
• C.Both A and B
• D.Neither A nor B

The inductance of a coil depends on

• A.Frequency of the current
• B.Resistance of the wire
• C.Capacitance of the coil
• D.Number of turns

Volt is equal to _?

• A.Joule/Coulomb
• B.Coulomb/Joule
• C.Joule × Coulomb
• D.Joule/Ampere

If we reverse the direction of electric current, then the direction of the magnetic field will be

• A.Reversed
• B.Remain the same
• C.Become zero
• D.Become perpendicular

What happens when you run a plastic comb through your dry and non-oily hair and then hold the comb above bits of paper?

• A.Bits of paper get instantly attracted to the comb
• B.Bits of paper are repelled away from the comb
• C.The comb melts and sticks to the paper
• D.No effect is observed on the bits of paper

Which of the following has a negative temperature coefficient of resistance?

• A.Copper
• B.Silver
• C.Thermistor
• D.Aluminium

A fuse in an electric circuit is used to _?

• A.Break the circuit when excessive current flows
• B.Increase the voltage in the circuit
• C.Regulate the power supply
• D.Convert AC to DC current

Ohm's law states that _?

• A.Current increases as voltage increases
• B.Current decreases as voltage increases
• C.Current remains constant regardless of voltage
• D.Voltage decreases as current increases