Q20 · 2025 · Paper 1Simple familiar1 mark
QUESTION 20
When a black body is heated, a graph with a distinctive peak is produced, as shown.
This black body curve can be used to demonstrate that
(A)
light behaves as a wave.
(B)
the frequency of light is constant.
(C)
light is quantised into discrete values.
(D)
the peak wavelength is proportional to the temperature of the object.
WORKED SOLUTION
1 markAnswer C
ANSWER
C
Worked solution
Planck’s explanation of the black-body spectrum requires energy exchange in discrete quanta. The curve therefore supports quantisation of light energy. Option C.
Selects option C.
Worked explanation by QCE Vault; correct option verified against the QCAA answer key.