Dual Nature of Matter and Radiation Practice Questions
NEET · Physics · 1634 free MCQs with instant results and detailed explanations.
1634
Total
403
Easy
702
Medium
529
Hard
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Topics in Dual Nature of Matter and Radiation
Einstein's Photoelectric Equation
507
de Broglie Hypothesis
571
Photoelectric Effect
556
Sample Questions from Dual Nature of Matter and Radiation
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Q1
Easy
What is the threshold frequency in the photoelectric effect?
A.
The minimum frequency required to eject electrons from a metal surface
B.
The maximum frequency of emitted electrons
C.
The frequency at which light is absorbed by a metal
D.
The frequency that causes maximum kinetic energy of emitted electrons
Show Answer & Explanation
Correct Answer: A
The threshold frequency is the minimum frequency needed to eject electrons from a metal surface during the photoelectric effect, as per Einstein's photoelectric equation.
Q2
Easy
If the frequency of incident light is doubled, what happens to the kinetic energy of the emitted electrons in the photoelectric effect?
A.
It doubles
B.
It increases four times
C.
It remains the same
D.
It halves
Show Answer & Explanation
Correct Answer: B
According to the photoelectric equation, kinetic energy is proportional to frequency. Therefore, if the frequency is doubled, the kinetic energy increases by a factor of four, since kinetic energy is proportional to the square of frequency.
Q3
Easy
In the photoelectric effect, which of the following factors does NOT affect the number of emitted electrons?
A.
Intensity of the incident light
B.
Frequency of the incident light
C.
Work function of the metal
D.
Color of the incident light
Show Answer & Explanation
Correct Answer: D
The color of the light is related to its frequency. While frequency and work function determine whether electrons are emitted, the color itself does not directly influence the number of emitted electrons. Intensity affects the number, while frequency must be above the threshold.
Q4
Medium
In the photoelectric effect, which of the following statements is TRUE regarding the relationship between the intensity of incident light and the number of emitted electrons?
A.
Higher intensity decreases the number of emitted electrons.
B.
Higher intensity increases the number of emitted electrons.
C.
Intensity does not affect the number of emitted electrons at all.
D.
Higher intensity changes the energy of the emitted electrons.
Show Answer & Explanation
Correct Answer: B
In the photoelectric effect, increasing the intensity of the incident light (while keeping frequency constant above the threshold) results in more photons striking the surface, thus increasing the number of emitted electrons. The energy of each emitted electron remains determined by the frequency of the incident light, not the intensity.
Q5
Medium
What happens to the photoelectric current if the frequency of incident light is decreased below the threshold frequency?
A.
Photoelectric current increases.
B.
Photoelectric current decreases.
C.
No photoelectric current is produced.
D.
Photoelectric current remains constant.
Show Answer & Explanation
Correct Answer: C
If the frequency of incident light falls below the threshold frequency, the energy of the photons is insufficient to overcome the work function of the material. As a result, no electrons are emitted, leading to no photoelectric current being produced.
Q6
Medium
What is the threshold frequency for a metal if its work function is 4.0 eV?
A.
9.65 x 10^14 Hz
B.
6.63 x 10^14 Hz
C.
1.24 x 10^15 Hz
D.
3.00 x 10^14 Hz
Show Answer & Explanation
Correct Answer: A
The threshold frequency (ฮฝโ) can be calculated using the formula ฮฝโ = ฯ/h, where ฯ is the work function and h is Planck's constant (6.63 x 10^-34 Jยทs). Converting 4.0 eV to joules gives us 6.4 x 10^-19 J. Therefore, ฮฝโ = (6.4 x 10^-19 J) / (6.63 x 10^-34 Jยทs) = 9.65 x 10^14 Hz.
Q7
Medium
Which of the following increases the number of photoelectrons emitted per second from a metal surface?
A.
Increasing the frequency of incident light
B.
Increasing the intensity of incident light
C.
Increasing the work function of the metal
D.
Decreasing the distance from the light source
Show Answer & Explanation
Correct Answer: B
Increasing the intensity of the incident light increases the number of photons striking the surface per unit time, leading to more photoelectrons being emitted if the light frequency exceeds the threshold frequency.
Q8
Hard
What is the minimum frequency of light required to eject electrons from a metal surface with a work function of 3.0 eV?
A.
5 ร 10^14 Hz
B.
7.5 ร 10^14 Hz
C.
3.75 ร 10^14 Hz
D.
6.0 ร 10^14 Hz
Show Answer & Explanation
Correct Answer: A
The minimum frequency, f, needed is given by the equation: f = W/h, where W is the work function and h is Planck's constant (6.626 ร 10^(-34) Js). This gives f = (3.0 eV ร 1.6 ร 10^(-19) J/eV) / (6.626 ร 10^(-34) Js) = 5 ร 10^14 Hz.
Q9
Hard
If the intensity of light is doubled while keeping the frequency constant, what will happen to the number of photoelectrons emitted?
A.
Doubles
B.
Remains the same
C.
Halves
D.
Increases four times
Show Answer & Explanation
Correct Answer: A
The number of photoelectrons emitted is directly proportional to the intensity of the incident light, as intensity relates to the number of photons. Doubling the intensity means twice as many photons will hit the surface, thus doubling the number of emitted electrons.
Q10
Hard
In the photoelectric effect, if the stopping potential is 5V, what is the maximum kinetic energy of the emitted electrons?
A.
5 eV
B.
2.5 eV
C.
10 eV
D.
7.5 eV
Show Answer & Explanation
Correct Answer: A
The maximum kinetic energy (KE) of emitted electrons is equal to the work done against the stopping potential. Thus, KE = eV = 1.6 ร 10^(-19) J ร 5 V = 5 eV.
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Dual Nature of Matter and Radiation โ NEET Physics Practice Questions Online
This page contains 1634 practice MCQs for the chapter Dual Nature of Matter and Radiation in NEET Physics. The questions are organized by difficulty โ 403 easy, 702 medium, 529 hard โ so you can choose the right level for your preparation.
Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit. This chapter covers 3 topics, giving you comprehensive coverage of the entire chapter.