Loudness, pitch, and timbre
It can't be less than 250 N or the cart wouldn't move at all. That means there is only 1 answer. It's between not enough info or 250 N. The answer is 250 N. If it was any more, there would be acceleration.
Answer:

Explanation:
Given:
- wavelength of light in the air,

- time taken to travel from the source to the photocell via air,

- time taken to reach the photocell via air and glass slab,

- thickness of the glass slab,

<u>Now we have the relation for time:</u>

hence,

c= speed of light in air



For the case when glass slab is inserted between the path of light:
(since light travel with the speed c only in the air)
here:
v = speed of light in the glass


Using Snell's law:



Option (D) is the correct one.
In order to increase the amount of work done, we need to increase the force applied to the object.
V = IR
By completing the equation, i found that the total power equation is : 4.8,
Which means that it's not exceed the power rating.
So i believe the answer would be : The string will remain lit
hope this helps