A ray of light passes through a right-angled prism as shown in the figure. State the angles of incidence at the face of AC and BC.
Angle of incidence at face AC = 45o
Angle of incidence at face BC = 0o
An inflated gas balloon is placed in a jar, which is connected to an evacuating pump. What will be observed if the air bubble inside the jar is pumped out? Give a reason justifying your answers.
When the air from jar is pumped out, the volume of the balloon will increase and it may even burst because, earlier the pressure of gas from inside was being counter acted by the outside pressure of air. But, this is not happening now.
A woman draws water from well using a fixed pulley. The mass of the bucket and water together is 6.0 kg. the force applied by the woman is 70 N. Calculate the mechanical advantage.
Weight of bucket = 6.0 x 10 = 60 N = Load
Define ‘critical angle’.
Critical angle is that angle of incidence in the denser medium corresponding to which the angle of refraction in the denser medium is 90o.
What is SONAR? State the principle on which it is based.
SONAR is an instrument, used for measuring the depth of the seas, by ultrasonic waves.
SONAR is based on the principle of echo.
A piece of ice floating in a glass of water but the level of water in the glass of water melts but the level of water in the glass does not change. Explain this phenomenon.
When a piece of ice floating in a glass of water melts, the level of water does not change because, the ice has already about 9/10 part of it submerged under water, which already makes a part of volume of water in the glass. So, after melting there is no change in the level of water.
Two bulls of mass ratio 1:2are dropped from the same height.
1. State the ratio between their velocities when they strike the ground and
m1: m2 = 1: 2
According to Newton's second law of motion,
F = ma
1. White light is passed through a yellow filter. What colour is (colours are) seen on a screen placed at the end.
2. If the light emerging from the yellow filter is then passed through red filter, what will be seen on the screen placed at the end?
1. Yellow, red and green are colors which are seen on the screen when white light is passed through the yellow filter.
2. If light emerging from a yellow filter is passed through a red filter only green light will be seen on the screen.
State the energy changes in an oscillating pendulum.
i) Initially, at point O, the bob is at rest.
When it starts moving towards a, its potential energy starts increasing and at point A it has maximum potential energy and zero kinetic energy. When it starts descending from A, its potential energy starts decreasing and kinetic energy starts increasing. Then at point O it has maximum kinetic energy and minimum potential energy. When it passes its mean position, the potential energy starts increasing and kinetic energy starts decreasing until again at point B, where it has maximum potential energy and zero kinetic energy.
Explain why scissors for cutting cloth may have blades much longer than the handles; but shears for cutting metals have short blades and long handles?
In case of scissors, blades may be much longer than the handles, because in this case we do not need much mechanical advantage.
(MA – Effort arm/ Load arm).
But, in case of scissors for cutting metals, much higher value of mechanical advantage is needed, to cut the metals easily, so the handles need to be long and blades short.