Answer:
3Q / 4 pi (R^3 - r^3)
Explanation:
Charge density = charge / volume
volume of a spherical shell = 
Answer:
Explanation: The field of a magnet is strongest at either pole of the magnet. it's equally strong at the North Pole when put next with the South Pole. The force is weaker within the middle of the magnet and halfway between the pole and also the center.
Answer:
Explanation:
Given
distance traveled by Passenger train is 
distance traveled by Freight train is 
Both take same time to travel
suppose speed of freight train is x mph
so speed of passenger train is 20+x mph
we know time
speed of passenger train 
This high specific heat of water prevents abrupt changes in temperature and helps the body maintain temperatures that are relatively constant.
Answer:
1.(c) 7
2.(d) 900
3.(b) two
4.(c) 0.0007
5.(d)0.0004
Explanation:
(1) White light after reflection through prism splits into 7 colors.
(2) Arabs and Chinese knew about lenses in about 900 AD
(3) There are Two more colors in the spectrum which cannot be seen with naked eye.
(4) Wavelength of red light is 0.0007mm
(5) Wavelength of violet light is 0.0004mm
