(a) Twice that of A
(b) 4 times that of A
(c) 1⁄4 that of A
(d) 1⁄2 that of A
Ans: (d)
86.Two thin convex lenses of focal lengths 4 cm and 8 cm are separated by a
distance of 4 cm in air. The combination will have the focal length? [NDA
2012]
(a) 4 cm
(b) 8 cm
(c) 12 cm
(d) 32 cm
Ans: (a)
87.In the isothermal process which of the following remains constant:
(a) temperature
(b) heat
(c) pressure
(d) density
Ans: (a)
88.In the adiabatic process which of the following remains constant:
(a) temperature
(b) heat
(c) pressure
(d) volume
Ans: (b)
89.For the adiabatic process ideal gas equation is expressed as :
(a) pVt = constant
(b) pVt-1
(c) pyVt-1 = constant
(d) any of these
Ans: (a)
90.For the isothermal process ideal gas equation is expressed as :
160