Physics - Online Test
Q1. The magnetic field due to a current carrying circular loop of radius 3 cm at a point on the axis at a distance of 4 cm from the centre is 54 μT. what will be its value at the centre of the loop?
Answer : Option D
Explaination / Solution:
The magnetic field at the centre of a coil of radius R and number of turns N , carrying a current I is . At a point distance x from the coil, the field is
Q2. What speed should a galaxy move with respect to us so that the sodium line at 589.0 nm is observed at 589.6 nm?
Answer : Option C
Explaination / Solution:
No Explaination.
Q3. A cube-shaped permanent magnet is made of a ferromagnetic material with a magnetization M of about The side length is 2 cm. Magnetic dipole moment of the magnet is.
Answer : Option B
Explaination / Solution:
No Explaination.
Q4. An N-type Ge is obtained on doping the Ge- crystal with
Answer : Option C
Explaination / Solution:
The addition of pentavalent impurities such as antimony, arsenic or phosphorous contributes free electrons, greatly increasing the conductivity of the intrinsic semiconductor.
Q5. A truck is coming towards you from a distance of 1000m on a straight road, at time t=0. It reaches you in 100sec. The average speed in m/s is
Answer : Option D
Explaination / Solution:
Total distance covered s = 1000 m
Total time taken t = 100-0 = 100 s
Average speed
Q6. There are three sources of sound of equal intensities with frequencies 400, 401 and 402 Hz. The number of beats per seconds is
Answer : Option B
Explaination / Solution:
No Explaination.
Q7. Plane electromagnetic wave travels in vacuum along z-direction. If the frequency of the wave is 30 MHz, its wavelength is
Answer : Option A
Explaination / Solution:
No Explaination.
Q8. A rectangular wire loop of sides 8 cm and 2 cm with a small cut is moving out of a region of uniform magnetic field of magnitude 0.3 T directed normal to the loop. What is the emf developed across the cut if the velocity of the loop is 1 cm in a direction normal to the longer side. For how long does the induced voltage last?
Answer : Option A
Explaination / Solution:
duration of |e| is
Q9.
Light of wavelength 4000 is incident on a metal plate whose work function is 2 eV. The maximum kinetic energy of the emitted photoelectrons would be
Answer : Option B
Explaination / Solution:
ϕ0=2eVλ=4000A∘E=123754000=3.1eVKmax=E−ϕ0=3.1−2=1.1eV
Q10. Audio signals have a maximum bandwidth of about
Answer : Option D
Explaination / Solution:
No Explaination.
