Physics - Online Test
Q1. A spring has a certain mass suspended from it and its period for vertical oscillations is . The spring is now cut into two equal halves and the same mass is suspended from one of the halves. The period of vertical oscillations is now .The ratio of / is
Answer : Option D
Explaination / Solution:
No Explaination.
Q2. In a coil of 0.1 m radius and 100 turns, 0.1 amp current is passed. What will be the magnetic field at the centre of the coil
Answer : Option C
Explaination / Solution:
Q3. The angle of incidence at which the reflected beam is fully polarized is called
Answer : Option C
Explaination / Solution:
No Explaination.
Q4. Nitric oxide is a paramagnetic compound. The magnetic moment of each NO molecule has a maximum component in any direction of about one Bohr magneton.Interaction energy of such magnetic moments in a 1.5-T magnetic field is
Answer : Option A
Explaination / Solution:
No Explaination.
Q5. The conductivity of P – type semiconductor is due to
Answer : Option A
Explaination / Solution:
No Explaination.
Q6. A truck is coming towards you from a distance of 1000m on a straight road at time t=0. At time t=10 seconds it is at a distance of 900 m. The average velocity in m/sec is
Answer : Option C
Explaination / Solution:
Initial distance x1 = 1000m
Initial time t1= 0 sec
Final distance x2 = 900 m
Final time t2 = 10 sec
Average velocity
=
Q7. Velocity of sound in air is 300 m/s. Then the distance between two successive nodes of a stationary wave of frequency 1000 Hz is.
Answer : Option A
Explaination / Solution:
No Explaination.
Q8.
What physical quantity is the same for X-rays of wavelength m, red light of wavelength 6800A and radio waves of wavelength 500m?
Answer : Option C
Explaination / Solution:
No Explaination.
Q9. Use Lenz’s law to determine the direction of induced current in the situations described by the Figure (a) A wire of irregular shape turning into a circular shape; (b) A circular loop being deformed into a narrow straight wire. The directions for (a) and (b) respectively are
Answer : Option C
Explaination / Solution:
(a) for a given Periphery the area of a circle is maximum. When a coil takes a circular shape, the magnetic flux linked with the coil increases, so the current induced in the coil will tend to decrease the flux and so it will produce a magnetic field upward. As a result the current induced in the coil will flow in anticlockwise direction.
(b) When circular coil takes the shape of narrow straight wire, The magnetic flux linked with the coil decreases. So the current induced in the coil will tend to oppose the decrease in magnetic flux. Hence it will produce an upward magnetic field so that the current induced in the coil will flow in anticlockwise direction.
Q10. The work function of a photoelectric material is 3.32 eV. The threshold frequency will be equal to
Answer : Option B
Explaination / Solution:
ϕ0=hν03.32×1.6×10−19=6.6×10−34×ν0ν0=3.32×1.6×10−196.6×10−34=8×1014Hz
