1 |
Light of frequency 2 times the threshold frequency is incident on the metalsurface. Ifthe frequency is by quartered and intensity is doubled, the photoelectric becomes |
Quadrupled
Zero
Doubled
Halved
|
2 |
In electron microscope, we use high speed electrons because them |
Penetration power is higher
Wavelength is smaller
Frequency is smaller
K.E is smaller
|
3 |
In photoelectric effect experiment, stopping potential depend upon |
Intensity of light
Frequency of light
Photoelectric current
Both A and B
|
4 |
de-Broglie wavelength associated with an electron moving at a speed of 1x106 ms-1 is |
4x10-10 ms-1
5x10-10 m
6x10-10 m
7x10-10 m
|
5 |
If an electron is accelerated such that its K.E is 4 times of its rest mass energythen thetotal relativistic energy of electrons is about |
5 × 10–12 J
4 × 10–13 J
3 × 10–13 J
6 × 10–12 J
|
6 |
Temperature of black body radiating at 270c is increased to 327oc, then emittedenergywill increase by |
2 times
12 times
16 times
4 times
|
7 |
A photo cell receives light from a source at 50 cm away and produces 40mAcurrent inthe circuit. When the same source at is at distance 1 m from photo cell,current in the circuit will be |
20 mA
80mA
60 mA
10 mA
|
8 |
Work function of all metals varies from 2 eV to 4eV. It is 4.2 eV for Aluminum and2eV for Sodium. If these two metals are illuminated by same light, the thresholdfrequency ofAluminum is |
Less than Sodium
Equal to that of Sodium
Grater than Sodium
Can’t be decided
|
9 |
Choose incorrect about properties of photon |
Rest mass of photon is zero
A photon is never at rest
Photon is not deflected by electric field not by magnetic field
The velocity of photon is different in different media
|
10 |
In photo electric cell, the photo electric current |
Decreases with increase in frequency of light
Depends on intensity and frequency of light
Does not depend upon the frequency of light and but depends upon intensity of light
Increases with increase in frequency of light
|
11 |
Intensity of light from a point source at the edge of unit sphere will be: |
𝑃
𝑃
P(4π)
4𝜋
|
12 |
Monochromatic light of wavelength 300 nm is incident normally on a surface of area 4 cm2. If the intensity of light is 150 mW/m2; the rate at which photon strike the surface: |
2.53 × 1019
7.5 × 1019
9.1 × 1013
2.53 × 1013
|
13 |
How many photons per second does a one-watt bulb emit if its efficiency is 10% and the wavelength of light is 500 nm: |
2.53 × 1017
2.53 × 1019
7.5 × 1019
7.5 × 1017
|
14 |
What will be the number of photons emitted per second by 25 W source of monochromatic light of wavelength 600 nm: |
7.5 × 1017
7.5 × 1019
5.5 × 1019
5.5 × 1017
|
15 |
What is the momentum of a photon of light of wavelength 500 nm in kgm/s: |
1.32 × 10−21
1.32 × 10−23
1.32 × 10−25
1.32 × 10−27
|
16 |
Which one is the correct express of de-Broglie equation for the length of atoms of mass m at temp? T(k=Boltzmann’s constant): |
<br>
|
17 |
The Balmer series is found in the spectrum of: |
Hydrogen
Nitrogen
Oxygen
All
|
18 |
When an electron in an atom goes from a lower to higher its: |
K.E. increases, P.E. decreases
K.E. increases
P.E increases
K.E. decrease, P.E. increases
|
19 |
The shortest wavelength of X-rays emitted from an X-rays tube depends on the: |
Current in the tube
Voltage applied to the tube
Nature of gas in the tube
Nature of material of tube
|
20 |
For X-rays which of the following is not correct: |
Cause of ionization in air when they pass through it
Can be deflected by electric and magnetic fields
Can be used to detect flaws in metal casting
Travel with the speed of light
|