NEET2020PhysicsElectromagnetic WavesActual
Light with an average flux of 20   W   cm - 2 falls on a non-reflecting surface at normal incidence having surface area 20   cm 2 . The energy received by the surface during time span of 1   min is:
Options
- A12 × 10 3   J
- B24 × 10 3   J
- C48 × 10 3   J
- D10 × 10 3   J
Correct answer
B. 24 × 10 3   J
Step-by-step solution
We know that, I = E A t E = I A t ⇒ E = 20 10 − 4 × 20 × 10 − 4 × 60 ⇒ E = 24 × 10 3   J