Question

The first two parts deal with the wave described below

In a given spot, there are two light waves:

One with an amplitude of   2100 N/C   

One with a value of   -3900 N/C

a.) What is the intensity of the resulting wave? (E=? N/C)

b.)What is the intensity of the resulting wave? ( I= ? Wm²)

on the next parts, consider two waves:

One with intensity of   40 W/m2   

One with intensity of   50 W/m2

c.) f the two waves add constructively, what is the absolute value of the resulting amplitude? (E= ?? N/C)

d.)If the two waves add destructively, what is the absolute value of the final amplitude? (E=?? N/C)

Answer 1

a) Enet = E1 + E2

= 2100 - 3900

= -1800 N/C <<<<<<<<<<<---------------Answer

b) we know, I = (1/2)*epsilon*c*E^2

= (1/2)*8.854*10^-12*3*10^8*1800^2

= 4303 W/m^2 <<<<<<<<<<<---------------Answer

c) let I1 = 40 W/m^2

I2 = 50 W/m^2

we know, I = (1/2)*epsilon*c*E^2

so, E1 = sqrt(2*I/(c*epsilon))

= sqrt(2*40/(3*10^8*8.854*10^-12))

= 174 N/C

E2 = sqrt(2*I/(c*epsilon))

= sqrt(2*50/(3*10^8*8.854*10^-12))

= 194 N/C

if the two waves add constructively,

Enet = E1 + E2

= 174 + 194

= 368 N/C <<<<<<<<<<<---------------Answer

d) If the two waves add destructively,

Enet = E2 - E1

= 194 - 174

= 20 N/C <<<<<<<<<<<---------------Answer