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A red LED emits light at 0.1 watt unifor...

A red LED emits light at 0.1 watt uniformly around it. The amplitude of the electric field of the light at a distance of 1 m from the diode is :

A

1.73 V/m

B

2.45 V/m

C

5.48 V/m

D

7.75 V/m

Text Solution

Verified by Experts

The correct Answer is:
B
Intensity `1=P/(4pir^2)` But i`=1/2in_0E_0""^2C`
`:. I=1/2in_0E_0^2xxC`
So `E_0=P/(4pir^2)=1/2in_0E_0^2xxC`
`E_0^2=(2P)/(4piin_0r^2C)=(2xx0.1xx9xx10^9)/(1xx3xx10^8)`
`E_0=sqrt6 =2.45` V/m.
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