I think its all four of them could be wrong but try all four !!!!!!
Answer:
a)
b)
Explanation:
a)
The width of the central bright in this diffraction pattern is given by:
when m is a natural number.
here:
- m is 1 (to find the central bright fringe)
- D is the distance from the slit to the screen
- a is the slit wide
- λ is the wavelength
So we have:
b)
Now, if we do m=2 we can find the distance to the second minima.

Now we need to subtract these distance, to get the width of the first bright fringe :
I hope it heps you!
Explanation:
Given that,
Mass of the rock climber, m = 90 kg
Original length of the rock, L = 16 m
Diameter of the rope, d = 7.8 mm
Stretched length of the rope, 
(a) The change in length per unit original length is called strain. So,

(b) The force acting per unit area is called stress.

(c) The ratio of stress to the strain is called Young's modulus. So,

Hence, this is the required solution.
Answer:
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it is c
Explanation: