Answer:
Double the current
Explanation:
The energy delivered by the heater is related to the current by the following relation:
E= 
let R * t = k ( ∴ R and t both are constant)
so E= k 
Now let:
E2= k I₂^2
E2= 4E
⇒ k I₂^2= 4* k 
Cancel same terms on both sides.
I₂^2= 4* 
taking square-root on both sides.
√I₂^2 = √4* I^2
⇒I₂= 2I
If we double the current the energy delivered each minute be 4E.
wavelength = speed/frequency
==> freq. = speed/wavelength = 342.5/0.75 = 456.67 Hz.
Diagram B .... light shines through at an angle