Short Answer TypeCan a simple machine act as a force multiplier and a speed multiplier at the same time?
Which class of lever found in the human body is being used by a boy:
i) When he holds a load on the palm of his hand.
ii) When he raises the weight of his body on his toes?A ray of light is moving from a rarer medium to a denser medium and strikes a plane mirror placed at 90o to the direction of the ray as shown in the diagram.
i) Copy the diagram and mark arrows to show the path of the ray of light after it is reflected from the mirror.
ii) Name the principle you have used to mark the arrow to show the direction of the ray.The refractive index of glass with respect to air is 1.5. What is the value of the refractive index of air with respect to glass?
A ray of light is incident as a normal ray on the surface of separation of two different medium. What is the value of the angle of incidence in this case?
i) Can the absolute refractive index of a medium be less than one?
ii) A coin is placed at the bottom of a beaker appears to be rasied by 4.0 cm. If the refractive index of water is 413, find the depth of water in the beaker?i) No.
ii) Given,
Shift = 4 cm ; 
; Real depth = ?
We know that,
Shift = Real depth
4 = Real depth 
Real depth = 
An object AB is placed between 2F1 and F1 on the principal axis of a convex lens as shown in the diagram.
A bucket kept under a running tap is getting filled with water. A person sitting at a distance is able to get an idea when the bucket is about to be filled.
i) What change take place in the sound to give this idea?
ii) What causes the change in the sound?A sound made on the surface of a lake takes 3 s to reach a boatman. How much time will it take to reach a diver inside the water at the same depth?
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