- A particle of charge –16 × 10–18 C moving with
velocity 10 m s–1 along the X-axis enters a region
where a magnetic eld of induction B is along
the y-axis and an electric eld of magnitude of
104 V m–1 is along the negative Z-axis. If the charged
particle continues moving along the X-axis, the
magnitude of B is
(a) 103 Wb m–2 (b) 105 Wb m–2
(c) 1016 Wb m–2 (d) 10 –3 Wb m–2 - e magnetic eld intensity due to a thin wire
carrying current I shown in gure is
(a)μ
π(^0) πα α
2
I
R
(t−+an )(b)μ
π(^0) πα
2
I
R
()−
(c)μ
π(^0) πα
2
I
R
()+
(d)μ
π(^0) πα α
2
I
R
(t+−an )- A circuit containing capacitors C 1 and C 2 , shown in
the gure, is in the steady
state with key K 1 close.
At the instant t = 0, K 1 is
opened and K 2 is closed.
e angular frequency of
oscillation of the circuit
and charge across C 1 at
t = 125 Ps are respectively.
(a) 25 × 10^3 rad s–1, 32 PC
(b) 5 × 10^4 rad s–1, 16 PC
(c) 5 × 10^4 rad s–1, –16 PC
(d) 25 × 10^3 rad s–1, –32 PC - A typical light dimmer
used to dim the stage
lights in a theatre consists
of a variable induction
L (where inductance is
adjustable between zero
and Lmax) connected in series with a light bulb
B as shown in gure. e mains electrical supply
is 220 V at 50 Hz, the light bulb is rated at 220 V,
1100 W. What Lmax is required if the rate of energy
dissipation in the light bulb is to be varied by a
factor of 5 from its upper limit of 1100 W?
(a) 0.69 H (b) 0.28 H
(c) 0.38 H (d) 0.56 H
RO
2 DI20 V8 PF 2 PFL = 0.2 mHRC 1 K 2 C 2K 1BulbBto mains- Two thin symmetrical lenses of di erent nature and
of di erent material have equal radii of curvature
R = 15 cm. e lenses are put close together and
immersed in water(Pw= 4/3). e focal length of the
system in water is 30 cm. e di erence between
refractive indices of the two lenses is
(a) 1/2 (b) 1/4 (c) 1/3 (d) 3/4 - e gure shows the initial position of a point
source of light S, a detector D and a lens L. Now at
t = 0, all the three start moving towards right with
di erent velocities as shown. e time(s) at which
the detector receives the maximum light is
(a) 0.56 s and 8.94 s (b) 3.8 s
(c) 8.94 s and 19.62 s (d) 0.56 s- If three times of Omin of continuous X ray spectrum
of target metal at 40 kV is same as the wavelength of
KD line of this metal at 30 kV, then nd the atomic
number of the target metal.
(a) 67 (b) 47 (c) 37 (d) 27 - Transitions between three energy levels in a
particular atom give rise to three spectral lines of
wavelengths, in increasing magnitudes, O 1 , O 2 and
O 3. Which one of the following equations correctly
relates O 1 , O 2 and O 3?
(a) O 1 = O 2 – O 3 (b) O 1 = O 3 – O 2
(c)111
λλ 12 λ 3=+ (d)111
λλ 13 λ 2=−
- Half-lives of two radioactive substances A and B
are, respectively, 20 min and 40 min. Initially, the
samples of A and B have equal number of nuclei.
Aer 80 min the ratio of the remaining number of
A and B nuclei is
(a) 1:16 (b) 4:1 (c) 1:4 (d) 1:1 - In semiconductor, the concentrations of electrons
and holes are 8 × 10^18 m–3 and 5 × 10^18 m–3,
respectively. If the mobilities of electrons and hole
are 2.3 m^2 V –1 s–1 and 0.01 m^2 V –1 s–1, respectively,
then semiconductor is
(a) N-type and its resistivity is 0.34 : m
(b) P-type and its resistivity is 0.034 : m
(c) N-type and its resistivity is 0.034 : m
(d) P-type and its resistivity is 3.40 : m