Circuits and electromagnetic induction

A cell of emf 12 V and internal resistance 1 ohm is connected to a 5 ohm resistor. What current flows?

• 1 12 A
• 2 2.4 A
• 3 2 A
• 4 6 A

A Wheatstone bridge is balanced when:

• 1 P / Q = R / S
• 2 P + Q = R + S
• 3 P x Q = R x S
• 4 P = S

Which law gives the direction of an induced current?

• 1 Ampere's law
• 2 Coulomb's law
• 3 Lenz's law
• 4 Ohm's law

A transformer has 100 turns in the primary and 500 turns in the secondary. If the input is 20 V, what is the output voltage?

• 1 4 V
• 2 500 V
• 3 20 V
• 4 100 V

Eddy currents are:

• 1 Loops of current induced in a conductor by a changing magnetic flux
• 2 Currents in a battery
• 3 Currents that flow only in insulators
• 4 Currents in a vacuum

The SI unit of resistivity is the:

• 1 Ohm
• 2 Ohm metre
• 3 Ohm per metre
• 4 Siemens

How much power is lost as heat when a current of 2 A flows through a wire of resistance 5 ohm?

• 1 10 W
• 2 40 W
• 3 20 W
• 4 2.5 W