The length of a simple pendulum is increased four times to its previous value while the mass is doubled. What is the ratio of the new and previous time period of the pendulum?

Which one of the following is NOT a basic property of electric charge?

What happens when the sunlight travels through the Earth’s atmosphere?

When a solid body is partially or completely immersed in a fluid, the fluid exerts an upward force on the body. The magnitude of the force is equal to
1.the mass of the body
2.the weight of the displaced fluid by the body
Which of the above is/are correct?