Cathode rays do not travel in straight lines.
Cathode rays do not penetrate through thick sheets.

Options

A. If both assertion and reason are true and the reason is the correct explanation of the assertion.
B. If both assertion and reason are true but reason is not the correct explanation of the assertion.
C. If assertion is true but reason is false
D. If assertion is false but reason is true.

Answer

D

Explanation

(d) We know that cathode rays cast shadows of solid objects placed in their path. During experiment performed on these rays, fluorescence (flash of light) is observed in the region, outside the shadow. This shows that cathode rays travel in straight lines. We also know that cathode rays penetrate through a thin sheet of metals but are stopped by thick sheets. Therefore assertion is false but the reason is true.