Recent questions tagged medium

A system of lens consists of two convex lenses of focal length $f_1= 30\;cm$ and $f_2 =20\;cm$. Separated by a distance 'd'. When a parallel beam of light is incident on the first lens after two refraction the resultant rays come out parallel then the distance 'd' is

asked Jan 22, 2014 by meena.p

1 answer

A convex lens of focal length 20 cm is placed glass slab of refractive index $\large\frac{3}{2}$.A parallel beam of light is incident on the convex lens. The light will converge.

asked Jan 22, 2014 by meena.p

1 answer

Sum of n terms of series $(n^2-1^2)$ + $2\;.(n^2-2^2)$ + $3\;.(n^2-3^2)$+.....is

asked Jan 22, 2014 by yamini.v

1 answer

Sum of n terms of series $\;1.3.5+3.5.7+5.7.9+$.......is

asked Jan 22, 2014 by yamini.v

1 answer

In an young double slit experiment the slit separation is 3 times the wave length of the light used What is the maximum number of interference maxima possible

asked Jan 22, 2014 by meena.p

1 answer

Three positive numbers $p, q, r$ are in HP, $(r > p)$, then $log (p+r) + log (p-2q+r)$ is equal to

asked Jan 22, 2014 by yamini.v

1 answer

$ \displaystyle\sum_ {i=o} ^{{m} ^{10}} C_i ^{20}C_{m-i}$ is maximum when $m=?$

asked Jan 21, 2014 by rvidyagovindarajan_1

1 answer

Which of the following is not a false statement?

asked Jan 21, 2014 by thanvigandhi_1

1 answer

Which of the following is a true statement?

asked Jan 21, 2014 by thanvigandhi_1

1 answer

Find $\frac{1}{3}+\frac{1}{15}+\frac{1}{15}+\frac{1}{35}+\frac{1}{63}+\frac{1}{99}$ +....upto n terms

asked Jan 21, 2014 by yamini.v

1 answer

Let A={2,3,5,7}. For which of the sets, truth value is true?

asked Jan 21, 2014 by thanvigandhi_1

1 answer

If $1$, $log_{b}^{a}$, $log_{c}^{b}$, $-15\;log_{a}^{c}$ are in AP, then

asked Jan 21, 2014 by yamini.v

1 answer

Two light waves whose equation are given respectively as $y_1 = 6\sin wt; y_2 =8 \sin (wt+ 8)$ super impose to form a interference pattern. The ratio of maximum to minimum intensities of the super imposed wave is

asked Jan 21, 2014 by meena.p

1 answer

$p, q, r$ are three unequal numbers in AP. If $q-p$, $r-q$ and $p$ are in GP, the $p\;:\;q\;:\;r$ equals

asked Jan 21, 2014 by yamini.v

1 answer

A man can view through telescope two district objects at a distance of $120 \;m$ from him if he uses light of $ \lambda= 550 A^{\circ}$ What must be minimum separation between objects if diameter of his pupil $D= 2.5 \;mm$

asked Jan 21, 2014 by meena.p

1 answer

For an AP with first term a and sum of first m terms 0, the sum of next n terms will be

asked Jan 21, 2014 by yamini.v

1 answer

Parallel beam of monochromatic light of wavelength $\lambda =4800 \mathring{A}$ is incident on a single slit of size $0.2 mm$ . The angular divergence in which most of light is diffracted is [ie between two 1st order maxima on both sides]

asked Jan 21, 2014 by meena.p

1 answer

If p, q, r are in increasing AP, then common difference will be

asked Jan 21, 2014 by yamini.v

1 answer

If the numbers $a, b, c, d, e$ are in AP, the value of $a-4b+6c-4d+e$ is

asked Jan 21, 2014 by yamini.v

1 answer

Sum of 20 terms of the series 1+2+3+4+5+8+7+16+9+....... is

asked Jan 21, 2014 by yamini.v

1 answer

The sum $1+\frac{3}{x}+\frac{9}{x^2}+\frac{27}{x^3}+....\infty$, ($x\neq\;0$) is finite if

asked Jan 21, 2014 by yamini.v

1 answer

A young's double slit experiment uses light of wavelength $900\; nm$ A plate of thickness 't' of material of refractive index $\mu=1.5$ i placed in front of one of the slits. What should be the thickness of plate 't' so that the central fringe becomes dark.

asked Jan 21, 2014 by meena.p

1 answer

If the numbers $\;1,x^2,6-x^2\;$ are in GP , then value of $x$ is :

asked Jan 21, 2014 by yamini.v

1 answer

If 20 is divided into four parts which are in AP such that ratio of product of first and fourth part and product of second and third part is 2:3, then the largest part is

asked Jan 21, 2014 by yamini.v

1 answer

$\displaystyle\sum_{r=1}^{n}\;\frac{r}{(r+1)!}=$

asked Jan 21, 2014 by yamini.v

1 answer