2018-10-01_Physics_For_You

(ii)

P d ca

b

v

(i)

v

× × ×

× × ×

× × ×

(a) a (b) b (c) c (d) d

5. An inductor of inductance L = 400 mH and resistors
   of resistances R 1 = 2 : and R 2 = 2 : are connected
   to a battery of emf 12 V as shown in the gure. e
   internal resistance of the battery is negligible. e
   switch S is closed at t = 0. e potential drop across
   L as a function of time is
   (a) 6e–5t V

(b)^123

t

e−tV

(c) 61

1

−^02

















−

e. V

(d) 12e–5t V

6. e horizontal component of the earth’s magnetic
   eld at a place is 4.0 × 10–4 T and the dip is 45°.
   A metal rod of length 20 cm is placed in the
   north-south direction and is moved at a constant
   speed of 5 cm s–1 towards east. Calculate the emf
   induced in the rod.
   (a) 4 × 10–6 V (b) 2 × 10–6 V
   (c) 6 × 10–4 V (d) 4 × 10–8 V

L

E

S R^2

R 1

NEET / AIIMS

Only One Option Correct Type

1. An emf of 15 V is applied in a circuit coil containing
   5 H inductance and 10 : resistance. e ratio of
   the currents at time t = f and t = 1 s is

(a)

e

e

12

(^121)
/
/ − (b)^
e
e
2
(^2) − 1
(c) 1 – e–1 (d) e–1

2. e resistance and inductance of series circuit are
   5 : and 20 H, respectively. At the instant of closing
   the switch, the current is increasing at the rate
   4 A s–1. e supply voltage (in V) is
   (a) 20 (b) 80 (c) 120 (d) 100


3. A pair of coils of turns n 1 and n 2 are kept close
   together. Current passing through the rst is
   reduced at the rate r, and emf 3 mV is developed
   across the other coil. If the second coil carries
   current which is then reduced at the rate 2r, then
   the emf produced across the rst coil will be

(a)

(^61)
2
n
n
mV (b)
(^62)
1
n
n
mV
(c) 6 mV (d)

3

2

mV

4. A conducting loop being pulled out of magnetic
   eld with a speed v. Which of the following plots
   may represent the power delivered by the pulling
   agent as a function of the speed v?

Electromagnetic Induction

and Alternating Current

Class XII

Total Marks : 120 Time Taken : 60 Min.