Paper 1 Electromagnetic Induction Drills

Q1

Magnetic flux through a flat coil is

A. $\Phi =BA\cos \theta$ where $\theta$ is angle between field and area normal.
B. $\Phi =B/A$.
C. $\Phi =V/I$.
D. $\Phi =It$.

Q2

Flux linkage is

A. $N\Phi$.
B. $\Phi /N$.
C. $BI/L$.
D. $qV$.

Q3

Faraday law states induced emf is related to

A. rate of change of flux linkage.
B. flux linkage only, not changing.
C. resistance only.
D. temperature gradient.

Q4

The minus sign in Faraday law represents

A. Ohm law.
B. Lenz law.
C. Coulomb law.
D. Snell law.

Q5

Lenz law is a statement of conservation of

A. charge only.
B. energy.
C. mass only.
D. wavelength.

Q6

No emf is induced in a coil when flux linkage is

A. changing.
B. constant.
C. increasing.
D. decreasing.

Q7

Motional emf in a straight rod moving perpendicular to $B$ and its length is

A. $\mathcal{E}=Blv$.
B. $\mathcal{E}=B/lv$.
C. $\mathcal{E}=I{R}^2$.
D. $\mathcal{E}=qBv$.

Q8

Increasing the number of turns in a coil for the same flux change and time

A. increases induced emf.
B. decreases induced emf.
C. has no effect.
D. reverses field only.

Q9

Eddy currents are induced currents in

A. bulk conductors.
B. insulators only.
C. isolated charges at rest.
D. vacuum.

Q10

Eddy currents can cause

A. heating and magnetic braking.
B. no energy transfer.
C. only capacitance.
D. only diffraction.

Q11

A faster magnet moving into a coil induces

A. larger emf.
B. smaller emf.
C. zero emf.
D. unchanged emf for all speeds.

Q12

When a magnet is stationary inside a coil, induced emf is

A. maximum.
B. zero.
C. infinite.
D. alternating necessarily.

Q13

The SI unit of magnetic flux is

A. weber.
B. tesla per metre.
C. farad.
D. coulomb.

Q14

The SI unit of flux linkage is

A. weber-turn.
B. volt per metre.
C. ohm.
D. newton per coulomb.

Q15

An induced current direction is such that its magnetic effect

A. assists the change causing it.
B. opposes the change causing it.
C. is random.
D. always points north.

Q16

For a sliding rod, mechanical work is needed because induced current causes

A. an opposing magnetic force.
B. zero force.
C. a gravitational force only.
D. no energy transfer.

Q17

If flux linkage varies as $N\Phi =kt$, induced emf magnitude is

A. $k$.
B. $kt$.
C. $k/t$.
D. zero always.

Q18

If flux linkage-time graph is curved, instantaneous emf magnitude is given by

A. area under graph.
B. gradient magnitude.
C. intercept only.
D. period only.

Q19

A transformer works by

A. mutual electromagnetic induction.
B. static charge transfer.
C. capacitance only.
D. chemical reaction.

Q20

A changing magnetic field can induce an emf even if there is

A. no closed conducting circuit.
B. no conductor anywhere.
C. no flux change.
D. no magnetic field.