An oxide coated filament is useful in vacuum tubes because essentially
it has high melting point
it can without and high temperature
it has good mechanical strength
it can emit electrons of relatively lower temperature
The Reynolds number of a flow is the ratio of
gravity to viscous force
gravity force to pressure force
inertia force to viscous force
viscous forces to pressure force
A monoatomic gas supplied the heat Q very slowly keeping the pressure constant. The work done by the gas will be
A mass m is suspended from the two springs ofspring constants k1 and k2 as shown. The time period of vertical oscillations of the mass will be
A copper wire and a steel wire of the same diameter and length are connected end to end and a force is applied which stretches their combined length by 1 cm. Then the two wires will have
the same stress and strain
the same stress but different strain
the same strain but different stress
different stress and strain
Rain drops are spherical in shape due to
acceleration due to gravity
downward motion
surface tension
capillary
For molecules of a gas have speeds 1, 2, 3 and 4 km/s. The value of the root mean square speed of the gas molecules is
2.5 km/s
D.
A simple pendulum of length l has a maximum angular displacement Q. The maximum kinetic energy of the bob is
mgl (1 - cosθ)
0.5 mgl
mgl
2 mgl
A step-up transformer has transformation ratio 3 : 2. The voltage in the secondary coil, if the voltage in the primary is 30 V will be
300 V
90 V
45 V
23 V