Physics - Online Test
Q1. Figure shows a capacitor made of two circular plates each of radius 12 cm, and separated by 5.0 cm. The capacitor is being charged by an external source (not shown in the figure). The charging current is constant and equal to 0.15A. Displacement current across the plates is
Answer : Option B
Explaination / Solution:
No Explaination.
Q2. A wheel with 10 metallic spokes each 0.5 m long is rotated with a speed of 60 rev/min in a plane normal to the horizontal component of earth’s magnetic field HE at a place. If HE = 0.4 G at the place, what is the induced emf between the axle and the rim of the wheel? Note that 1 G = 10–4 T.
Answer : Option D
Explaination / Solution:
e=12Bωl2=12×0.4×10−4×2×3.14×1×0.5×0.5=3.14×10−5V
ω=2πn
n=60/60=1rev/sec
Q3. A photon behaves as if it had a mass equal to
Answer : Option A
Explaination / Solution:
No Explaination.
Q4. Fourier series of a repeating sine wave has a
Answer : Option C
Explaination / Solution:
No Explaination.
Q5. A man can swim with a speed of 4.0 km/h in still water. How long does he take to cross a river 1.0 km wide if the river flows steadily at 3.0 km/h and he makes his strokes normal to the river current? How far down the river does he go when he reaches the other bank?
Answer : Option A
Explaination / Solution:
Speed of the man, vm = 4 km/h
Width of the river = 1 km
Time taken to cross the river =
Speed of the river, vr = 3 km/h
Distance covered with flow of the river = vr × t
= 750 m
Q6. When a negatively charged conductor is connected to earth,
Answer : Option A
Explaination / Solution:
After earthing a positively charged conductor electrons flow from earth to conductor and if a negatively charged conductor is earthed then electrons flows from conductor to earth.
Q7. Figure shows the strain-stress curve for a given material. What is the approximate yield strength for this material?
Answer : Option C
Explaination / Solution:
No Explaination.
Q8. A cylinder with a movable piston contains 3 moles of hydrogen at standard temperature and pressure. The walls of the cylinder are made of a heat insulator, and the piston is insulated by having a pile of sand on it. By what factor does the pressure of the gas increase if the gas is compressed to half its original volume?
Answer : Option A
Explaination / Solution:
PVγ=ConstPVγ=Pf(V2)γforH2,γ=1.4Pf=P21.4=2.64P
Q9. In comparison to atomic size in Rutherford’s model, the size of the atom in Thomson’s model is
Answer : Option D
Explaination / Solution:
No Explaination.
Q10. A constant force acting on a body of mass 3.0 kg changes its speed from 2.0 m to 3.5 m in 25 s. The direction of the motion of the body remains unchanged. What is the magnitude and direction of the force?
Answer : Option C
Explaination / Solution:
