A circular plate of area $0.4 c m^{2}$ is kept at distance of 2m from isotropic(uniform in all directions) source of power $π$ W. Find the amount of energy received by plate in 5 secs.

Open in App

Solution

Energy emitted by speaker is $π J$

Energy will be transmitted in all directions that is in spherical shape
Therefore energy at 2m $E = \frac{π}{4 π r^{2}} = \frac{π}{4 π 2^{2}} = \frac{1}{16}$

Energy on the circular plate $E_{p} = 0.4 \times 10^{- 4} \times \frac{1}{16} = 2.5 \times 10^{- 8} J$

Energy fall in 5 sec $2.5 \times 10^{- 8} \times 5 = 12.5 \times 10^{- 6} J = 12.5 μ J$

Suggest Corrections

Similar questions

Q. A circular plate of area

0.8 {cm}^{2}

is kept at a distance of

2 m

from a source of sound of power

π W

. Find the amount of energy received by the plate in

4 s

Q. A circular plate of area

0.8 {cm}^{2}

is kept at a distance of

2 m

from a source of sound of power

π W

. Find the amount of energy received by the plate in

4 s

Q. A photographic plate placed at a distance of

5 c m

from a weak point source is exposed for

3 s

. if the plate is kept at a distance of

10 c m

from the source, the time needed for the same exposure is

Q. A small metal plate (work function

= 2 e V

) is placed at a distance of

2 m

from a monochromatic light source of wavelength

4.8 \times 10^{- 7}

m and power

1.0

watt. The light falls normally on the plate. The number of photons striking the metal plate per second per unit area will be

The intensity of light $I_{1}$ received by the emitter plate in Lenard's photoelectric set-up is changed by moving the source to twice the initial distance. What is the new intensity $I_{2}$ received by the emitter plate?

Join BYJU'S Learning Program

A circular plate of area 0.4cm2 is kept at distance of 2m from isotropic(uniform in all directions) source of power π W. Find the amount of energy received by plate in 5 secs.

Energy emitted by speaker is πJEnergy will be transmitted in all directions that is in spherical shapeTherefore energy at 2m E=π4πr2=π4π22=116Energy on the circular plate Ep=0.4×10−4×116=2.5×10−8JEnergy fall in 5 sec 2.5×10−8×5=12.5×10−6J=12.5μJ

A circular plate of area $0.4 c m^{2}$ is kept at distance of 2m from isotropic(uniform in all directions) source of power $π$ W. Find the amount of energy received by plate in 5 secs.