Did you try looking it up ?
Answer:
Part a)
Width of the slit is

Part b)
Ratio of intensity is given as

Explanation:
Part a)
As we know by the formula of diffraction we will have

so we have


so we will have


Part b)
As we know that the intensity in diffraction pattern is given as


so for angle 45 degree



Answer:
v = 79.2 m/s
Solution:
As per the question:
Mass of the object, m = 250 g = 0.250 kg
Angle, 
Coefficient of kinetic friction, 
Mass attached to the string, m = 0.200 kg
Distance, d = 30 cm = 0.03 m
Now,
The tension in the string is given by:
(1)
Also
T = m(g + a)
Thus eqn (1) can be written as:





Now, the speed is given by the third eqn of motion with initial velocity being zero:

where
u = initial velocity = 0
Thus


Answer:
Explanation:
If you look closely, force 1 does not reach 0.2 until 0.4 force 2 reaches 0.2 at about 0.2 - hope that made sense :P