Answer:
The distance between the slits is given by 1.3 ×
m
Given:

D = 4 m
y = 
m = 1
To find:
distance between slits, d = ?
Formula used:
y = 
y = distance of first bright band from central maxima
D = distance between screen and source
d = distance between slits
= wavelength
Solution:
distance of first bright band from central maxima is given by,
y = 
y = distance of first bright band from central maxima
D = distance between screen and source
d = distance between slits
= wavelength
Thus,
d = 
d = 
d = 1.28 × 
d = 1.3 ×
m
The distance between the slits is given by 1.3 ×
m
Answer:
Electric flux, 
Explanation:
It is given that,
Electric field, 
We need to find the electric flux through a circular area of radius 2.66 m that lies in the xy-plane. 
The electric flux is given by :


Since, k.k=i.i=j.j = 1
So,


So, the electric flux through a circular area is
.Hence, this is the required solution.
Explanation: Slowing Down (or Stopping) occurs when the force of kinetic friction is greater than that of the external force. This also follows Newton's first law of motion as there exists a net force on the object.
Answer:
Explanation:
Given
Each student exert a force of 
Let mass of car be m
there are 18 students who lifts the car
Total force by 18 students 
therefore weight of car 
mass of car 

(b)
Answer:
(a) The force between them quadruples
Explanation:
According to coulomb's law, initial force between the two charged objects is given as;

where;
k is coulomb's constant
q₁ is the charge on the first object
q₂ is the charge on the second object
r is the distance between the two objects
When the charges on both objects are doubled, then;
q₁ = 2q₁
q₂ = 2q₂
Force between the two charged objects will become

Therefore, the force between them quadruples