Physics - Online Test
Q1. A wire connected to a power
supply of 230 V has power dissipation P1. Suppose the wire is cut
into two equal pieces and connected parallel to the same power supply. In this
case power dissipation is P2. The ratio P2 / P1
is
Answer : Option D
Explaination / Solution:
Q2. The ratio of the wavelengths for the transition
from n =2 to n = 1 in Li++, He+ and H is
Answer : Option D
Explaination / Solution:
Q3. Two identical coils, each
with N turns and radius R are placed coaxially at a distance R as shown in the
figure. If I is the current passing through the loops in the same direction,
then the magnetic field at a point P which is at exactly at R/2 distance
between two coils is
Answer : Option B
Explaination / Solution:
Q4. The light emitted in an LED is due to
Answer : Option A
Explaination / Solution:
No Explaination.
Q5. In a transformer, the number of turns in the primary and the secondary are 410 and 1230 respectively. If the current in primary is 6A, then that in the secondary coil is
Answer : Option A
Explaination / Solution:
Q6. The alloys used for muscle wires in Robots are
Answer : Option A
Explaination / Solution:
No Explaination.
Q7. In an electromagnetic wave
in free space the rms value of the electric field is 3 V m−1. The
peak value of the magnetic field is
Answer : Option A
Explaination / Solution:
Q8. The radius of curvature of curved surface at a thin planoconvex lens is 10 cm and the refractive index is 1.5. If the plane surface is silvered, then the focal length will be,
Answer : Option B
Explaination / Solution:
For
a plano-convex lens with its plane surface silvered
1/f = 2(n − 1)/R
f = R / 2(n − 1) = 10 / 2(1.5 − 1) = 10 / 2(0.5) = 10 cm
Q9. 
One of the of Young’s double slits is covered with
a glass plate as shown in figure. The position of central maximum will,
Answer : Option B
Explaination / Solution:
No Explaination.
Q10. Rank the electrostatic
potential energies for the given system of charges in increasing order.
Answer : Option A
Explaination / Solution:
