CGPET 2019 Solved Paper

Given,
The ratio of maximum intensity to minimum intensity is

Imax

Imin

=25
Now, in the interference,
∴ Intensities of two coherent sources is given by

Imax

Imin

=

(√I1+√I2)2

(√I1−√I2)2

or 25=

(√I1+√I2)2

(√I1−√I2)2

or √25=

(√I1+√I2)

(√I1−√I2)

5=

√I1+√I2

√I1−√I2

or 5(√I1−√I2)=√I1+√I2
or 5√I1−√I1=√I2+5√I2
or √I1(5−1)=√I2(5+1)
or

√I1

√I2

=

6

4

⇒

I1

I2

=(

6

4

)2
or

I1

I2

=

36

16

⇒

I1

I2

=

9

4

Therefore, the intensities of the sources are in the ratio 9:4.