IB Physics HL E.2.2 Threshold frequency

[Maximum number: 3]

This question is in two parts. Part 1 is about the oscillation of a mass. Part 2 is about the photoelectric effect.
Part 1 Oscillation of a mass
A mass of 0.80 kg rests on a frictionless surface and is connected to two identical springs both of which are fixed at their other ends. A force of 0.030 N is required to extend or compress each spring by 1.0 mm . When the mass is at rest in the centre of the arrangement, the springs are not extended.

(a)

Part 2 Photoelectric effect
A student carries out a photoelectric experiment in which radiation is incident on a metal surface in a vacuum.

Explain why photoelectrons are not emitted from the metal surface unless the frequency of incident light exceeds a minimum value.

[ 2 ]

(b)

A graph of the results of the experiment show how the maximum kinetic energy $E_{\text {max }}$ of the emitted photoelectrons varies with the frequency f of the incident radiation.

Use the graph to

[ 1 ]

(i)

identify the minimum value of the frequency $f_{0}$ for photoelectrons to be emitted.

[ 1 ]

(value of intercept on f-axis $=) 9.3 \times 10^{14} \mathrm{~Hz}$ ;
Allow answers in the range of 9.0 to 9.5, but with correct power of ten.

IB Physics HL E 2 2 Hl Threshold Frequency Questions

Exam points

IB Physics HL E 2 2 Hl Threshold Frequency Questions question 1

Question (a)

Question (b)

Question (i)