Physics Test - ...

In a potentiometer, for a cell of emf \(1.5 {~V}\), the balance point is obtained at \(42.0 {~cm}\) length. If the cell is replaced by another cell, the balance point is obtained at \(63.0 {~cm}\) length. Find the emf of the second cell.

A motor having an armature of resistance \(2 \Omega\) is designed to operate at \(220 ~V\) mains. At full speed, it develops a back emf of \(210 ~V\). What is the current in the armature when the motor is running at full speed?

A particle of mass m is moving along the x-axis such that its velocity is given by \(v=k \sqrt{x}\). The work done by the force during the first t seconds is:

Two wires of same length and radius are joined end to end and loaded. The Young's modulii of the materials of the two wires are \(Y_1\) and \(Y_2\). The combination behaves as a single wire then its Young's modulus is :

Unit of magnetic flux is:

A Proton and an alpha particle both are accelerated through the same potential difference. The ratio of corresponding de-Broglie wavelengths is:

Which of the following statements is true/false regarding charged particle?

A. An ion is a charged particle and can be negatively or positively charged. A negatively charged ion is called an anion and a positively charged ion, a cation

B. An ion is a charged particle and can be negative or positively charged. A negatively charged ion is called a cation. And a positively charged ion, an anion.

Two blocks of masses \(1 k g\) and \(2 k g\) are connected by a metal wire going over a smooth pulley. The breaking stress of metal is \(\frac{40}{3 \pi} \times 10^{6} N m^{-2} .\) What should be the minimum radius of wire used if it should not break? \(\left(g=10 m s^{-2}\right)\)

If a simple pendulum is taken to a place where g decreases by \(2 \%\) then the time period: