Q. No.An α-particle moves in a circular path of radius 0.83 cm in the presence of a magnetic field of 0.25 Wb/m2. The de-Broglie wavelength associated with the particle will be:
1.
1 ˚A
2.
0.1 ˚A
3.
10 ˚A
4.
0.01 ˚A
1. 200p
2. 400p
3. p200
4. 100p
In the Davisson and Germer experiment, the velocity of electrons emitted from the electron gun can be increased by
1. increasing the filament current
2. decreasing the filament current
3. decreasing the potential difference between the anode and filament
4. increasing the potential difference between the anode and filament
A radioactive nucleus of mass M emits a photon of frequency ν and the nucleus recoils. The recoil energy will be:
1. h2ν2/2 Mc2
2. zero
3. hν
4. Mc2-hν
Photoelectric emission occurs only when the incident light has more than a certain minimum
1. wavelength
2. intensity
3. frequency
4. power
The threshold frequency for a photo-sensitive metal is 3.3×1014 Hz. If the light of frequency 8.2×1014 Hz is incident on this metal, the cut-off voltage for the photo-electric emission is nearly:
1. 2 V 2. 3 V
3. 5 V 4. 1 V
| 1. | 2.4 V | 2. | −1.2 V |
| 3. | −2.4 V | 4. | 1.2 V |
| 1. | N and 2T | 2. | 2N and T |
| 3. | 2N and 2T | 4. | N and T |
The figure shows a plot of photo current versus anode potential for a photo sensitive surface for three difference radiations. Which one of the following is a correct statement?
1. Curves a and b represent incident radiations of different frequencies and different intensities
2. Curves a and b represent incident radiations of same frequency but of different intensities
3. Curves b and c represent incident radiations of different frequencies and different intensities
4. Curves b and c represent incident radiations of same frequency having same intensity
| 1. | 2.7×10−18 ms−1 |
| 2. | 9×10−2 ms−1 |
| 3. | 3×10−31 ms−1 |
| 4. | 2.7×10−21 ms−1 |
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