Question

pls help me...............urgent

Answer 1

4.1 seconds make a solar day

Answer 2

1)1)Reflection of light
    When an incident ray hits a smooth mirror then there is a deviation of the light ray back to the same medium from which it came. The light rays always follow the laws of reflection.

2)Fuse
    When excess heat flows at a socket or even when the live wire and neutral wire come in contact  it is called a fuse.

4)1)Our eyes have the ability to contract and expand to allow the required amount of light on the retina so as to minimise the damage. Looking at the sun directly allows so much light that our eyes contract so much that after a few seconds we close our eye.To prevent damage to retina we must not look at the sun directly.

5)1)When parallel rays of light hit a plane mirror , the light ray returns back to the same medium undeviated. In a concave mirror , they converge at the focus and in a convex lens they diverge and appear to meet at the focus behind the mirror.

5)3)When current is passed through a solenoid , then the metal piece present in the solenoid acts as an electromagnet. The strength  of magnetic field of this depeds on the number of coils of the solenoid and the magnitude of current.

5)5)A lens is a refracting object that changes the direction of light.
A concave lens is called a diverging lens because , parallel rays of light appear to meet at the focus of the lens but actually diverge in the opposite direction.
Hence they are known as diverging lens.