# Electrons used in an electron microscope are accelerated by a voltage of 25 kV. If the voltage is increased to 100 kV, then the de-Broglie wavelength associated with the electrons would: 1.  decrease by 2 times 2.  decrease by 4 times 3.  increase by 4 times 4.  increase by 2 times

Subtopic:  De-broglie Wavelength |
74%
From NCERT
AIPMT - 2011
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

A source S1 is producing 1015 photons per sec of wavelength 5000 Å. Another source S2 is producing 1.02×1015 photons per second of wavelength 5100 Å. Then, (power of S2)/(power of S1) is equal to:

1. 1.00

2. 1.02

3. 1.04

4. 0.98

Subtopic:  Photoelectric Effect: Experiment |
75%
From NCERT
AIPMT - 2010
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface, having work function 5.01 eV, when ultraviolet light of 200 nm falls on it, must be:

1. 2.4 V

2. -1.2 V

3. -2.4 V

4. 1.2 V

Subtopic:  Einstein's Photoelectric Equation |
61%
From NCERT
AIPMT - 2010
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

Monochromatic light of wavelength 667 nm is produced by a helium-neon laser. The power emitted is 9mW. The number of photons arriving per second on average at a target irradiated by this beam is:
1. 9 x 1017

2. 3 X 1016

3. 9 x 1015

4. 3 X 1019

Subtopic:  Photoelectric Effect: Experiment |
78%
From NCERT
AIPMT - 2009
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

The figure shows a plot of photocurrent versus anode potential for a photosensitive surface for three different 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 radiation of the same frequency but of different intensities. 3 Curves $$b$$ and $$c$$ represent incident radiation of different frequencies and different intensities. 4 Curves $$b$$ and $$c$$ represent incident radiations of the same frequency having the same intensity.
Subtopic:  Photoelectric Effect: Experiment |
85%
From NCERT
AIPMT - 2009
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

The number of photoelectrons emitted for the light of a frequency $\nu$ (higher than the threshold frequency $\nu$0) is proportional to:
1. $\nu$ -$\nu$0
2. threshold frequency ($\nu$0)
3. intensity of light
4. frequency of light ($\nu$)
Subtopic:  Photoelectric Effect: Experiment |
78%
From NCERT
AIPMT - 2009
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

The work function of the surface of a photosensitive material is $$6.2$$ eV. In which region does the wavelength of the incident radiation, for which the stopping potential is $$5$$ V, lie?
1. ultraviolet region.
2. visible region.
3. infrared region.
4. X-ray region.

Subtopic:  Einstein's Photoelectric Equation |
52%
From NCERT
AIPMT - 2008
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

In the phenomenon of electric discharge through gases at low pressure, the colored glow in the tube appears as a result of:
 1 excitation of electrons in the atoms 2 a collision between the atoms of the gas 3 collisions between the charged particles emitted from the cathode and the atoms of the gas 4 a collision between different electrons of the atoms of the gas

Subtopic:  Electron Emission |
69%
From NCERT
AIPMT - 2008
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

A particle of mass $$1$$ mg has the same wavelength as an electron moving with a velocity of  $$3\times 10^{6}$$ ms-1. The velocity of the particle is:
(Mass of electron = $$9.1 \times 10^{-31}$$ kg)
1. $$2.7 \times 10^{-18}~\text{ms}^{-1}$$
2. $$9 \times 10^{-2}~\text{ms}^{-1}$$
3. $$3 \times 10^{-31}~\text{ms}^{-1}$$
4. $$2.7 \times 10^{-21}~\text{ms}^{-1}$$

Subtopic:  De-broglie Wavelength |
53%
From NCERT
AIPMT - 2008
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

A $$5$$ W emits monochromatic light of wavelength $$5000~\mathring{A}$$. When placed $$0.5$$ m away, it liberates photoelectrons from a photosensitive metallic surface. When the source is moved $$1.0$$ m away, the number of photoelectrons liberated is reduced by a factor of?
1. $$4$$
2. $$8$$
3. $$16$$
4. $$2$$

Subtopic:  Electron Emission |
71%
From NCERT
AIPMT - 2007
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints