Physics - Online Test
Q1. In an N-P-N transistor, P-type crystal is
Answer : Option A
Explaination / Solution:
When the p-type crystal is grown between relatively wide sections of n-type crystals then the transistor is called NPN transistor.
Q2. A truck has a velocity of 3 m /s at time t=0. It accelerates at 3 m / on seeing police .What is its velocity in m/s at a time of 2 sec
Answer : Option B
Explaination / Solution:
Initial velocity u = 3 m/s
Acceleration a = 3 m/s2
Initial time
Final time
Time taken t = 2-0= 2 s
Final velocity v = ?
We know,
Q3. Two waves of wavelength 1m & 1.01 m produce 10 beats in 3 sec. The velocity of sound in a gas is about
Answer : Option A
Explaination / Solution:
No Explaination.
Q4. A horizontal ring of radius r spins about it's axis with an angular velocity ω in a uniform magnetic field of magnitude B. Emf induced in the ring is
Answer : Option B
Explaination / Solution:
Induced EMF is zero because flux linked with it remains constant
Q5. Part of the electromagnetic spectrum to which 5890Ao - 5896Ao [double lines of sodium] belongs is
Answer : Option B
Explaination / Solution:
No Explaination.
Q6. Threshold frequency of a photon required to eject a photoelectron from the surface of cesium is
Answer : Option A
Explaination / Solution:
No Explaination.
Q7. need for modulation also arises from
Answer : Option C
Explaination / Solution:
No Explaination.
Q8. Passengers on a carnival ride move at constant speed in a horizontal circle of radius 5.0 m, making a complete circle in 4.0 s. What is their acceleration?
Answer : Option B
Explaination / Solution:
The speed is constant, so this is uniform circular motion. We are given the radius R=5.0 m and the period T=4.0 s, so we can calculate the acceleration directly using equation
== 12m/s2
Q9. Gravitational force is the smallest between
Answer : Option B
Explaination / Solution:
Gravitational force is given by Since the masses are small in case of two pens and / so the gravitational force is very small.
Q10. A rigid bar of mass 15 kg is supported symmetrically by three wires each 2.0 m long. Those at each end are of copper and the middle one is of iron. Determine the ratios of their diameters if each is to have the same tension.
Answer : Option C
Explaination / Solution:
No Explaination.
