blowing air over a liquid aids evaporation by
increasing its surface area
decreasing its vapour pressure
increasing its temperature
decreasing its density
Correct answer is B
if you blow dry air over the glass you blow away this extra water vapor, thereby decreasing the amount of water vapor entering the glass.
a ray of light which strikes a glass slab from air at normal incidence passes through the slab
undeviated and undisplaced at a lower speed
deviated and undisplaced at a lower speed
deviated and displaced at a lower speed
undeviated and displaced at a faster speed
Correct answer is A
The angle of refraction will be zero as the angle of incidence is zero in this case. This is a rule, that whenever a ray strikes perpendicularly or normally to a surface, no refraction will take place and hence the ray will pass through without deviating from its path.
water is a poor thermometric liquid because it
is opaque
is a poor conductor
wets glass
has low vapour pressure
Correct answer is B
No explanation has been provided for this answer.
10 cm
30 cm
40 cm
60 cm
Correct answer is B
if r = 40 cm , then f = r/2 = 40/2 = 20 cm
then for a real image by a concave mirror,
magnification M = f/u-f => 2 = 20/U-20
therefore 2(u-20) = 20
2u - 40 = 20
2u = 40 + 20
2u = 60/2 = 30 cm
528 ms-1
264 ms-1
132 ms-1
66 ms-1
Correct answer is B
in a vibrating string the fundamental frequency is given by fo = v/2L
therefore velocity = 2L x f.
= 2 x 0.6 x 220
= 264 m/s.