Let I(n) = 2cos nx ∀n∈N, then I (1).I(n+1) - I(n) is equal to
I(n+3)
I(n+2)
I(n+1).I(2)
I(n) = 2cosnx ⇒ I(1).I(n+1) - I(n)
= 4cosx cos(n+1)x - 2cosnx
= 2[2cos(n+1)x cosx - cosnx]
= 2[cos(n+2)x + cosnx - cosnx]
= 2 cos(n+2)x = I(n+2)
Let I (n)=2cos n x, nϵN, then I(1)I(n+1)-I(n)=___
Two waves of intensity l2 and I2 interfere. The maximum intensity produced to the minimum intensity is in the ratio a . Then, I1/I2is equal to