The box of a pin hole camera, of length L, has a hole of radius a. It is assumed that when the hole is illuminated by a parallel beam of light of wavelength the spread of the spot (obtained on the opposite wall of the camera) is the sum of its geometrical spread and the spread due to diffraction. The spot would then have its minimum size (say bmin) when :

The Boolean Expression (p   q)  q  ( p  q) is equivalent to :

A man is walking towards a vertical pillar in a straight path, at a uniform speed. At a certain point A on the path, he…

Let two fair sixfaced dice A and B be thrown simultaneously. If E1 is the event that die A shows up four, E 2 is the e…

If the standard deviation of the numbers 2, 3, a and 11 is 3.5, then which of the following is true?

Let a, b and c be three unit vectors such that    3a b c b c . 2    If b is not parallel to c , then the angle…

If the line, x 3 y 2 z 4 2 1 3  lies in the plane, x + my  z = 9, then 2 + m2 is equal to :

The distance of the point (1, 5, 9) from the plane x  y + z = 5 measured along the line x = y = z is :

The eccentricity of the hyperbola whose length of the latus rectum is equal to 8 and the length of its conjugate axis i…

The centres of those circles which touch the circle, x 2 + y2  8x  8y  4 = 0, externally and also touch the x-axis,…

Two sides of a rhombus are along the lines, x  y + 1 = 0 and 7x  y  5 = 0. If its diagonals intersect at (1, 2), t…