Two convex lenses have focal lengths of 50 cm and 25 cm, respectively. If these two lenses are placed in contact, then the net power of this combination will be equal to

Which one of the following terms cannot represent electrical power in a circuit?

The refractive index of crown glass is close to 3/2. If the speed of light in air is c, then the speed of light in the crown glass will be close to

The volume of a sealed packet is 1 liter and its mass is 800 g. The packet is first put inside the water with a density of 1 g cm^-3 and then in another liquid B with a density of 1.5 g cm^-3. Then which one of the following statements holds true?