Physics - Online Test
Q1. A closely wound solenoid of 800 turns and area of cross section carries a current of 3.0 A.It is free to turn about the vertical direction and a uniform horizontal magnetic field of 0.25 T is applied.Magnitude of torque on the solenoid when its axis makes an angle of with the direction of applied field
Answer : Option A
Explaination / Solution:
No Explaination.
Q2. Shape of the wave front of light diverging from a point source is
Answer : Option B
Explaination / Solution:
When light diverges from a point source it moves in the form of diverging spherical wavefront.
Q3. Two infinitely long wires carry currents in opposite directions. Then the field at a point P lying midway between them is
Answer : Option C
Explaination / Solution:
When two wires carry currents in the same direction, the magnetic field lines at any point midway between them have the same direction. The magnitudes of the fields add up. If the current in the wires are the same, the field at the midpoint will have twice the magnitude of the field produced by each wire.
Q4. The number of terminals in a transistor is/are
Answer : Option A
Explaination / Solution:
A transistor is an electronic component that can be used as an amplifier, or as a switch. It is made of semiconductor material. Transistors are found in most electronic devices. 
A transistor has three connectors or terminals. In the older bipolar transistor they are the collector, the emitter, and the base. The flow of charge goes in the collector, and out of the emitter, depending on the charge flowing to the base
Q5. A jet lands on an aircraft carrier at 30 m/s. It stops in 2.0 s? What is the displacement of the plane in m while it is stopping?
Answer : Option C
Explaination / Solution:
Initial velocity u = 30 m/s
As it stop so final velocity v = 0 m/s
Time t = 2 s
Distance covered = s
We know,
s =
=> s = 30 m
Q6. When a wave undergoes reflection at rarer medium then it undergoes a phase difference of
Answer : Option C
Explaination / Solution:
No Explaination.
Q7. Expression for the mutual inductance between a long straight wire and a square loop of side a as shown in figure is
Answer : Option D
Explaination / Solution:
dA=adrB=μ04π2irϕ=∫BdA=∫xx+aμ04π2iradrϕ=μ0a2πln(1+1x)
Q8. State the part of the electromagnetic spectrum to which 21 cm (wavelength emitted by atomic hydrogen in interstellar space).belongs
Answer : Option B
Explaination / Solution:
No Explaination.
Q9. If a potential of volts is applied across the electrodes of a CRT, then speed attained by the electrons is approximately (given: 1.76 C/kg)
Answer : Option A
Explaination / Solution:
No Explaination.
Q10. A transmitting antenna at the top of a tower has a height 32 m and the height of the receiving antenna is 50 m. What is the maximum distance between them for satisfactory communication in LOS mode? Given radius of earth is 6.4 m.
Answer : Option B
Explaination / Solution:
No Explaination.
