Question

The energy flow per unit time per unit area (S) of an electromagnetic wave has an average value of 695 mW/m^2. The wave is incident upon a rectangular area, 1.5 m by 2.0 m, at right angles. The total energy that traverses the area in a time interval of one minute is closest to:

Answer 1

The total energy is 125.1 J.

Step-by-step explanation:

Given that,

Intensity
`S =695 mW/m^2`

Area
`A= 1.5*2.0=3\ m^2`

The light intensity of a electromagnetic wave

`S=(P)/(A)`

`P=SA`....(I)

We know that,

`P=(E)/(t)`....(II)

We need to calculate the total energy that traverses the area

From equation (I) and (II)

`E=SAt`

Where, A = area

t = time

S = intensity

Put the value into the formula

`E=695*10^(-3)*3*60`

`E=125.1\ J`

Hence, The total energy is 125.1 J.