(R/r)2
r/R
(r/R)2
R/r
Correct answer is D
In a wheel and axle system of mechanic, the mechanical advantage is given by its ratio of the radius of the wheel R, to the radius of the axle r. that M.A = R/r
The pair of physical quantities consisting of vectors only are
momentum and power
velocity and distance
displacement and torgue
accelaration and speed
Correct answer is C
No explanation has been provided for this answer.
16cm
6cm
8cm
12cm
Correct answer is B
for a real image 3 times the size of the object, it implies that the magnification 3 = v/u, 3 = 24/u, therefore 3u = 24, u = 8cm thus we have from the relation:m = (f)/(u)-f; that 3 = (f)/(8) - f. therefore f = 3(8-f) f = 24 - 3f ∴4f = 24; f = 6cm OR: (1)/(u) + (1)/(v) = (1)/(f).
(1)/(8) + (1)/(24) = (1)/(f)
therefore (3+1)/(24) = (1)/(f)
4/24=1/f;therefore 4f = 24
f = 6cm
A thin converging lens has a power of 4.0 diopters determined its focal length.
2.50m
0.03m
5.00m
0.25m
Correct answer is D
the power of a lens is defined as the reciprocal of the focal length ,expressed in metre.Mathematically, the power of a lens in dioptres is given by:(1)/f(in cm).
thus for lens of power of 4.0 dioptres we have that: (1)/(f) = +4.0
f= (1)/(4.0)
= 0.25cm
The sharpness of the boundary of the shadow of an object is determined by the
intensity of light striking the object
rays of light passing through the object
nature of the object
opacity of the object
Correct answer is B
The sharpness of the boundary of the shadow of an object is determined by the rays of light passing through the object. The smaller the rays passing through , that is from a point source, the more sharp the shadow becomes, but the more the rays, that is rays from a large source, the more blurred the shadow becomes.