A lamp delivers a luminous flux of 100 W to an absorber of area 1 cm 2. The force due to radiation pressure is

Question

A lamp delivers a luminous flux of 100 W to an absorber of area 1 cm 2. The force due to radiation pressure is (A) 3.3 × 10-4 N (B) 16.5 × 10-7 N (C) 3.3 × 10-6 N (D) 3.3 × 10-7 N

Tardigrade Admin · Accepted Answer

∵ Force = Rate of change of linear momentum F=(d p/d t)=(d/d t)((v/c))=(1/c) (d v/d t) where, v= electromagnetic wave energy. or F=(I/c)=(100/3 × 108)=33.3 × 10-8 N or F=3.3 × 10-7 N

Q. A lamp delivers a luminous flux of $100 W$ to an absorber of area $1 c m^{2}$ . The force due to radiation pressure is

$3.3 \times 1 0^{- 4} N$

$16.5 \times 1 0^{- 7} N$

$3.3 \times 1 0^{- 6} N$

$3.3 \times 1 0^{- 7} N$

$∵$ Force $=$ Rate of change of linear momentum
$F = \frac{d p}{d t} = \frac{d}{d t} (\frac{v}{c}) = \frac{1}{c} \frac{d v}{d t}$
where, $v =$ electromagnetic wave energy.
or $F = \frac{I}{c} = \frac{100}{3 \times 1 0 ^{8}} = 33.3 \times 1 0^{- 8} N$
or $F = 3.3 \times 1 0^{- 7} N$

Q. A lamp delivers a luminous flux of 100W to an absorber of area 1cm2. The force due to radiation pressure is

3.3×10−4N

16.5×10−7N

3.3×10−6N

3.3×10−7N