Question

The electric field intensity produced by the radiations coming from100 W bulb at a 3m distance is E. The electric field intensity produced by the radiations coming from 50 W bulb at the same distance is

• A. $\frac{E}{2}$
• B. 2E
• C. $\frac{E}{\sqrt{2}}$
• D. $\sqrt{2}E$

Answer 1

Answer: (A)

$\frac{E}{2}$

Answer 2

: Electric field intensity on a surface due the incident radiation is.

$E = \frac{U}{At} = \frac{P}{A}\left( \because\frac{U}{t} = P \right)$

$\therefore E \propto P$ (for the given area of the surface)

$\therefore\frac{E'}{E} = \frac{P'}{P} = \frac{50}{100} = \frac{1}{2}$

$E' = \frac{E}{2}$