Which of the following statements are correct, if the threshold frequency of caesium is 5.16 × 1014 Hz?

Photoelectric Effect on Caesium | JEE Mains PYQ | Structure of Atom

Q. Which of the following statements are correct, if the threshold frequency of caesium is 5.16 × 10¹⁴ Hz?

A. When Cs is placed inside a vacuum chamber with an ammeter connected to it and yellow light is focused on Cs, the ammeter shows the presence of current.

B. When the brightness of the yellow light is dimmed, the value of the current in the ammeter is reduced.

C. When a red light is used instead of the yellow light, the current produced is higher with respect to the yellow light.

D. When a blue light is used, the ammeter shows the formation of current.

E. When a white light is used, the ammeter shows formation of current.

Choose the correct answer from the options given below:

A. B, C and D only

B. A, C, D and E only

C. A, B, D and E only

D. A, D and E only

Explanation

Step 1: Threshold frequency concept

Photoelectric emission occurs only if frequency of incident light is greater than or equal to threshold frequency.

Step 2: Yellow light

Frequency of yellow light is greater than threshold frequency of Cs, so current is produced. Hence, statement A is correct.

Step 3: Effect of intensity

Reducing brightness reduces number of emitted electrons, therefore current decreases. Statement B is correct.

Step 4: Red light

Red light has frequency less than yellow light and may be below threshold, so it cannot produce higher current. Statement C is incorrect.

Step 5: Blue and white light

Blue light has higher frequency than threshold, so photoelectric effect occurs. White light contains high-frequency components, so current is produced. Statements D and E are correct.

Correct Answer = A, B, D and E only

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