KVPY Government Jobs Exams

A cylindrical copper rod has length L and resistance R. If it is melted and formed into another rod of length 2L, the resistance will be
option
(A) R
(B) 2R
(C) 4R
(D) 8R

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KVPY Other Question

A convex lens is used to form an image of an object on a screen. If the upper half of the lens is blackened so that it becomes opaque, then
option
(A) only half of the image will be visible
(B) the image position shifts towards the lens
(C) the image position shifts away from the lens
(D) the brightness of the image reduces A 750 W motor drivers a pump which lifts 300 litres of water per minute to a height of 6 meters. The efficiency of the motor is nearly (take acceleration due to gravity to be 10 m/s2)
option
(A) 30%
(B) 40%
(C) 50%
(D) 20%