Physics Test 19...

A thin semi-circular ring of radius r has a positive charge q distributed uniformly over it. The net electric field  at the centre O is

Figure shows three circular arcs, each of radius R and total charge as indicated. The net electric potential at the centre of curvature is

Two rods are joined end to end, as shown. Both have a cross-sectional area of 0.01 cm2. Each is 1 meter long. One rod is of copper with a resistivity of 1.7 × 10–6 ohm-centimeter, the other is of iron with a resistivity of 10–5 ohm-centimeter. How much voltage is required to produce a current of 1 ampere in the rods?

A charged particle moves through a magnetic field perpendicular to its direction. Then

A thin rectangular magnet suspended freely has a period of oscillation equal to T. Now it is broken into two equal halves (each having half of the original length) and one piece is made to oscillate freely in the same field. If its period of oscillation is T ' , the ratio T'/T is

A plane electromagnetic wave in a non-magnetic dielectric medium is given by  with distance being in meter and time in seconds. The dielectric constant of the medium is :

To get three images of a single object, one should have two plane mirrors at an angle of

The wave fronts of a light wave travelling in vacuum are given by x + y + z = c. The angle made by the direction of propagation of light with the X-axis is