AIEEE 2003 (Physics) Mock Test

Curie temperature is the temperature above which:

A spring balance is attached to the ceiling of a lift. A man hangs his bag on the spring and the spring reads $49\text{N}$, when the lift is stationary. If the lift moves downward with an acceleration of $5{\text{m/s}}^2$, the reading of the spring balance will be:

The length of a wire of a potentiometer is $100\text{cm}$, and the e.m.f. of its standard cell is $E$ volt. It is employed to measure the e.m.f. of a battery whose internal resistance is $0.5\Omega$. If the balance point is obtained at $l=30\text{cm}$ from the positive end, the e.m.f. of the battery is:

A strip of copper and another of germanium are cooled from room temperature to $80\text{K}$. The resistance of:

Consider telecommunication through optical fibres. Which of the following statements is not true?