## CBSE PMT – 2007 SCREENING PAPER

PHYSICS

1. The primary and secondary coil of a transformer have 50 and 1500 turns respectively. If the magnetic flux f linked with the primary coil is given by f = f0 + 4t, where f is in webers, t is time in seconds and f0 is a constant, the output voltage across the secondary coil is
(a) 120 volts (b) 220 volts
(c) 30 volts (d) 90 volts
2. A beam of electron passes undeflected through mutually perpendicular electric and magnetic fields. If the electric field is switched off, and the same magnetic field is maintained, the electrons move
(a) in a circular orbit
(b) along a parabolic path
(c) along a straight line
(d) in an elliptical orbit.
3. The position x of a particle with respect to time t along x-axis is given by x = 9t2 – t3 where x is in metres and t in second. What will be the position of this particle when it achieves maximum speed along the +ve x direction?
(a) 54 m (b) 81 m (c) 24 m (d) 32 m. 4. A particle starting from the origin (0, 0) moves in a straight line in the (x, y) plane. Its coordinates at a later time are ( 3,3) . The path of the particle makes with the x-axis an angle of
(a) 45o (b) 60o (c) 0o (d) 30o 5. A car moves from X to Y with a uniform speed vu and returns to Y with a uniform speed vd.