Ans : (a)
292. The lines of force of a uniform magnetic field: [NDA 2011]
           (a) must be convergent
           (b) must be divergent
           (c) must be parallel to each other
           (d) intersect
Ans : (c)
293. If the electrical resistance of a typical substance suddenly drops to zero, then the substance is called: [NDA 2011]
           (a) super conductor
           (b) semiconductor
           (c) conductor
           (d) insulator
Ans : (a)
294. In a pressure cooker cooking is faster because the increase in vapour pressure: [NDA 2011]
           (a) increases the specific heat
           (b) decreases the specific heat
           (c) decreases the boiling point
           (d) increases the boiling point
Ans : (c)
295. Magnets attract magnetic substances such as iron, nickel; cobalt etc. They can also repel·: [NDA 2011]
           (a) paramagnetic substances
           (b) ferromagnetic substances
           (c) diamagnetic substances
           (d) non-magnetic substances
Ans : (c)
296. When a ray of light is going from one medium to another, its: [NDA 2011]
           (a) wavelength remains same
           (b) frequency remains same
           (c) frequency increases
           (d) wavelength increases
Ans : (b)
297. Water is a good coolant and is used to cool the engines of cars, buses, trucks, etc. It is because water has a [CDS 2011]
           (a) high specific heat
           (b) low surface tension
           (c) high boiling point
           (d) low expansivity
Ans : (a)
The velocity-time (v-t) graph shown above illustrates [CDS 2011]
     (a) uniform acceleration of an object