Two identical photo-cathodes receive light of frequencies $f_{1} a n d f_{2}$ . If the velocities of the photo electrons (of mass m) coming out are respectively $v_{1} a n d v_{2}$ , then

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A particle is moving along vertical circle of radius R inside a smooth hollow sphere. If V1,V2 are velocities of particle at the highest and lowest points of vertical circle respectively, then which of the following expression is true?

The correct option is D V22−V21=4gRFor the particle to move in a circle inside the hollow sphere, it needs to have an critical velocities.i.e V2=√5gR and V1=√gR ∴V22−V21=4gR

A particle is moving along vertical circle of radius R inside a smooth hollow sphere. If $V_{1}, V_{2}$ are velocities of particle at the highest and lowest points of vertical circle respectively, then which of the following expression is true?

The correct option is D $V_{2}^{2} - V_{1}^{2} = 4 g R$
For the particle to move in a circle inside the hollow sphere, it needs to have an critical velocities.
i.e $V_{2} = \sqrt{5 g R}$ and $V_{1} = \sqrt{g R}$
$∴ V_{2}^{2} - V_{1}^{2} = 4 g R$