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Recent questions tagged boardexam
Questions
A capacitor of unknown capacitance,a resistor of $100 \Omega$ and an inductor of self inductance $L= (4/\pi ^2)$ hentry are connected in series to an ac source of 200 V and 50 Hz. Calculate the value of the capacitance and impedance of the circuit When the current is in phase with the voltage. Calculate the power dispersal in the circuit .
cbse
class12
physics
boardexam
2016
sec-e
asked
Jun 7, 2016
by
meena.p
1
answer
(i) Explain briefly the process of emanation of light by light emitting Diode (LED). (ii) Which semiconductor are provided to make LED and why ? (iii) Give two advantages of using LED over conventional incandescent lamps
cbse
class12
physics
boardexam
2016
sec-e
asked
May 30, 2016
by
meena.p
1
answer
Two harmonic waves of monochromatic light : $y_1$ = n const and $y_2 =a \cos (wt + \phi)$ are superimposed on each other. Show that maximum intensity in interference pattern is four times the intensity due to each slit. Hence write the condition for constructive and destructive interference in terms of the phase angle $\phi $
cbse
class12
physics
boardexam
2016
sec-e
asked
May 30, 2016
by
meena.p
1
answer
What is electrostatic shielding ? . How is this properly used in actual practice ? Is the potential in the cavity of a charged conductor zero ?
cbse
class12
physics
sec-b
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
Write briefly the underlying principle used in Davison - germer experiment to verify wave nature of electron experimentally. What is the de- Broglie wavelength of an electron with kinetic energy (K.E) 120 eV?
cbse
class12
physics
sec-b
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
State two properties of electromagnetic waves.How can we show that em waves carry momentum ?
cbse
class12
physics
sec-b
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
Write the functions of a (i) transducer and (ii) repeater in a communication system.
cbse
class12
physics
sec-b
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
The energy levels of a hypothetical atom are shown below. Which of the shown transitions will result in the emission of photon wave length.
cbse
class12
physics
sec-b
boardexam
2016
asked
May 30, 2016
by
meena.p
0
answers
In the ground state of hydrogen atom, its Bohr radius is given as $5.3 \times 10^{-11}\;m$ . The atom is excited such that the radius becomes $21.2 \times 10^{-11}\;m$ . Find (i) the value of the principal quantum number and (ii) the total energy of the atom in this excited state.
cbse
class12
physics
sec-b
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
The power factor of an a.c circuit is 0.5 . What is the phase difference between voltage and current in the circuit ?
cbse
class12
physics
sec-a
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
In which situation is there a displacement current but no conduction current ?
cbse
class12
physics
sec-a
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
Define the term relaxation time in a conductor .
cbse
class12
physics
sec-a
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
Two wires one of copper and other of manganin have same resistance and equal length. Which wire is thicker and why ?
cbse
class12
physics
sec-a
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
Name of the logic gates marked P and Q in the given circuit
cbse
class12
physics
sec-a
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
Three numbers are selected at random (with out replacement ) from first six positive integers. If X denotes the smallest of the three numbers obtained , find the probability distribution of X.Also find the mean and variance of the distribution .
cbse
class12
math
sec-c
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
A diet is to contain at least 80 units of vitamin A and 100 units of minerals. Two foods \( F_1 \: and F_2\) are available . Food \( F_1 \) costs Rs. 4 perunit and \( F_2\) costs Rs. 6 per unit. One unit of food \( F_1 \) contains 3 units of vitamin A and 4 units of minerals. One unit of food \( F_2 \) contains 6 units of vitamin A and 3 units of minerals. Formulate this as a linear programming problem and find graphically the minimum cost for diet that consists of mixture of these two foods and also meets the minimal nutritional requirements.
cbse
class12
math
sec-c
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
Find the equation of the plane containg two parallel lines $ \large\frac{x-1}{2} = \frac{y+1}{-1} = \frac{z}{3} $ and $\large\frac{x}{4} = \frac{y-2}{-2} =\frac{z+1}{6}$ . Also find the plane thus obtained contains the line $ \large\frac{x-2}{3} =\frac{y-1}{1} =\frac{z-2}{5}$ or not .
cbse
class12
math
sec-c
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
Using integration find the area of the region $f(x,y): y^2 \leq 6ax$ and $ x^2+y^2 \leq 16a^2$
cbse
class12
math
sec-c
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
Find the maximum and minimum values of $f(x)=\sec x + \log \cos ^2x, 0 < x < 2 \pi$
cbse
class12
math
sec-c
boardexam
2016
asked
May 30, 2016
by
meena.p
0
answers
Determine the intervals in which the function $f(x)=x^4 -8x^3+22x^2-24 x +21$ is strictly increasing or strictly decreasing.
cbse
class12
math
sec-c
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
Using of elementary row operations, find the inverse of the following matrix : $\begin{bmatrix} 2 & -1 & 3\\ -5 & 3 & 1\\-3 & 2 & 3\end{bmatrix}$
cbse
class12
math
sec-c
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
Using properties of determinant prove that : $\begin{bmatrix}(b+c)^2 & a^2 & bc \\ (c+a)^2 & b^2 & ca \\ (a+b)^2 & c^2 & ab \end{bmatrix}$ $=(a-b)(b-c)(c-a) (a+b+c)(a^2+b^2+c^2)$
cbse
class12
math
sec-c
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
Find the coordinates of the point where the line $ \overrightarrow {r} =(-\hat {i} - 2 \hat {j} - 3 \hat {k} )+ \lambda ( 3\hat i + 4 \hat j +3 \hat k )$ meets the plane which is perpendicular to the vector $ \overrightarrow n= \hat i + \hat j + 3 \hat k$ and at a distance of $\large\frac{4}{\sqrt {11}}$ from origin .
cbse
class12
math
sec-b
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
Find the equation of plane passing through the point $A(3,2,1,) B(4,2,-1)$ and $C(6,5,-1)$ and $D(\lambda,5,5)$ are co planar
cbse
class12
math
sec-b
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
Given that vectors $ \overrightarrow{a},\overrightarrow{b},\overrightarrow{c}$ from a triangle such that $\overrightarrow{a} = \overrightarrow{b}+ \overrightarrow{c}$. Find p,q,r,s such that area of triangle is $ 5 \sqrt 6$ where $\overrightarrow{a} = p \hat i +q \hat j +r \hat k$ ,$\overrightarrow{b} = s \hat i +3 \hat j +4 \hat k$ and $\overrightarrow{c} = 3 \hat i + \hat j -2 \hat k$
cbse
class12
math
sec-b
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
There are two bags A and B . Bag A contains 3 white and 4 red balls whereas bag B contains 4 white and 3 red balls . Three balls are drawn at random ( with out replacement ) from one of the bags and are found to be two white and one red. Find the probability that these were drqwn from bag B.
cbse
class12
math
sec-b
boardexam
2016
asked
May 30, 2016
by
meena.p
1
answer
Solve the equation for $x: \cos ( \tan ^{-1} x ) = \sin \bigg( \cot ^{-1} \large\frac{3}{4}\bigg)$
cbse
class12
math
sec-b
boardexam
2016
asked
May 27, 2016
by
meena.p
0
answers
Prove that $ 2\sin ^{-1} \bigg( \large\frac{3}{5} \bigg) - \tan ^{-1} \bigg(\large\frac{17}{31} \bigg) = \large\frac{\pi}{4}$
cbse
class12
math
sec-b
boardexam
2016
asked
May 27, 2016
by
meena.p
1
answer
Ishan wants to donate a rectangular plot of land for a land for a school in his village . When he was asked to give dimensions of the plot, he told that if its length is decreased by 50 m and breadth is increased by 50 m, then its area will remain same. but if length is decreased by 10 m and breadth is decreased by 20 m. then its area will decrease by $5300\;m^2$ . Using matrices , find the dimension of the plot. Also give reasons why he wants to denote the plot for a school.
cbse
class12
math
sec-b
boardexam
2016
asked
May 27, 2016
by
meena.p
1
answer
Solve the differential equation : $ 2ye^{x/y} dx+ (y -2x e^{x/y})dy=0$
cbse
class12
math
sec-b
boardexam
2016
asked
May 27, 2016
by
meena.p
1
answer
Solve the differential equation : $(x+1)\large\frac{dy}{dx}$$-y =e^{3x}(x+1)^3$
cbse
class12
math
sec-b
boardexam
2016
asked
May 27, 2016
by
meena.p
1
answer
Evaluate : $\int \limits_0^1 \cot ^{-1} (1-x+x^2)dx$
cbse
class12
math
sec-b
boardexam
2016
asked
May 27, 2016
by
meena.p
1
answer
Evaluate: $ \int \limits_0^{\large\frac{\pi}{2}} \large\frac{sin ^2 x}{\sin x + \cos x}$$dx$
cbse
class12
math
sec-b
boardexam
2016
asked
May 27, 2016
by
meena.p
1
answer
Find $\{\int (\log (\log x)+\large\frac{1}{(\log x)^2}\}$$dx$
cbse
class12
math
sec-b
boardexam
2016
asked
May 27, 2016
by
meena.p
1
answer
Find $\int \large\frac{1- \sin x}{\sin x (1+\sin x)}$$dx$
cbse
class12
math
sec-b
boardexam
2016
asked
May 27, 2016
by
meena.p
1
answer
Find the equation of normal to the curve $ay^2 = x^3$ at the point whose x coordinate is $am^2$
cbse
class12
math
sec-b
boardexam
2016
asked
May 27, 2016
by
meena.p
1
answer
Find k, if $f(x) = \left\{ \begin{array} {1 1} k \sin \frac{\pi}{2}(x+1), & \quad x \leq 0 \\ \frac{\tan x - \sin x}{x^3} ,& \quad x >0 \end{array} \right. $ is a continuous at x=0
cbse
class12
math
sec-b
boardexam
2016
asked
May 27, 2016
by
meena.p
1
answer
Differentiate $\tan ^{-1} \bigg( \large\frac{\sqrt{1+x^2}-\sqrt{1-x^2}}{\sqrt{1+x^2}+\sqrt{1-x^2}}\bigg)$ with respect to $ \cos ^{-1}x^2$
cbse
class12
math
sec-b
boardexam
2016
asked
May 27, 2016
by
meena.p
1
answer
Differentiate $(\sin 2x)^x+ \sin ^{-1} \sqrt {3x}$ with respected to x
cbse
class12
math
sec-b
boardexam
2016
asked
May 27, 2016
by
meena.p
1
answer
If $A = \begin{bmatrix} 0 & 3 \\2 & -5 \end{bmatrix}$ and $KA = \begin{bmatrix} 0 & 4a \\-8 & 5b \end{bmatrix}$ find the values of K and a
cbse
class12
math
sec-a
boardexam
2016
asked
May 27, 2016
by
meena.p
1
answer
If $A= \begin{bmatrix}1 & 2 \\ 3 & -1\end{bmatrix}$ and $B=\begin{bmatrix}1 & -4 \\ 3 & -2\end{bmatrix}$ find $|AB|$
cbse
class12
math
sec-a
boardexam
2016
asked
May 27, 2016
by
meena.p
1
answer
If A is a square matrix such that $|A|=5$ write the value of $|AA^T|$
cbse
class12
math
sec-a
boardexam
2016
asked
May 27, 2016
by
meena.p
1
answer
Find the distance between the planes $\overrightarrow {r}.(2 \hat i - 3 \hat j +6 \hat k)-4=0 $ and $\overrightarrow {r} . (6 \hat i - 9 \hat j +18 k )+30=0 $
cbse
class12
math
sec-a
boardexam
2016
asked
May 27, 2016
by
meena.p
1
answer
If $\overrightarrow {a} $ and $\overrightarrow {b} $ are unit vectors , then what is the angle between $\overrightarrow {a} $ and $\overrightarrow {b} $ for $\overrightarrow {a} - \sqrt 2 \overrightarrow {b} $ to be a unit vector ?
cbse
class12
math
sec-a
boardexam
2016
asked
May 27, 2016
by
meena.p
1
answer
If vectors $\overrightarrow {a} $ and $\overrightarrow {b}$ are such that $|\overrightarrow {a}| = \large\frac{1}{2}$, $|\overrightarrow {b}| = \large\frac{4}{\sqrt 3}$ and $|\overrightarrow {a} \times \overrightarrow {b}| = \large\frac{1}{\sqrt 3}$ then find $|\overrightarrow {a}. \overrightarrow {b}|$
cbse
class12
math
sec-a
boardexam
2016
asked
May 27, 2016
by
meena.p
1
answer
A dietician wants to develop a special diet using two foods X and Y. Each packet (contains 30g) of food X contains 12 units of calcium , 4 units of iron, 6 units of cholesterol and $6 \;units$ of vitamin A. Each packet of the same quantity of food Y contains 3 units of calcium, 20 units of iron , 4 units of cholesterol and 3 units of vitamin A. The diet requires at least 240 units of calcium , at least 460 units of iron and at most 300 units of cholesterol. Make an LPP to find how many packets of each food should be used to minimise the amount of vitamin A in the diet, and solve it graphically.
class12
cbse
boardexam
2015
set-1
sec-c
math
modelpaper
asked
Mar 23, 2015
by
meena.p
1
answer
A dealer deals in two items only - item A and item B . He has $Rs. 50,000$ to inverst and a space to store at most 60 items. An item A cost $Rs. 2500$ and item B costs $Rs. 500$. A net profit to him on item A is $Rs. 500$ and on item B is $Rs. 150$. If he can sell all the items that he purchases , how should he inverst his amount to have maximum profit ? Formulate an LPP and solve is graphically .
class12
cbse
boardexam
2015
set-1
sec-c
math
modelpaper
asked
Mar 23, 2015
by
meena.p
1
answer
Assume that the chances of a patient having a heart attack is $40\%$ . It is also assumed that a meditation and yoga course reduces the risk of heart attack by $30\%$ and the prescription of a certain drug reduces its chance by $25\%$ . At a time a patient can choose any one of the two options with equal probabilities . Its given that after going through one of the two options the patient selected at random suffers a heart attack. Find the probability that the patient followed a course of mediation and yoga.
class12
cbse
boardexam
2015
set-1
sec-c
math
modelpaper
asked
Mar 23, 2015
by
meena.p
1
answer
Find the vector and cartesian equation of the plane passing through the intersection of the planes $\overrightarrow {r} . (\hat i +\hat j+ \hat k)=6$ and $\overrightarrow {r} . (2\hat i +3\hat j+ 4 \hat k)=-5$ and the point $(1,1,1)$
class12
cbse
boardexam
2015
set-1
sec-c
math
modelpaper
asked
Mar 23, 2015
by
meena.p
1
answer
Solve the following differential equation , given that $y=0$ , then $ x= \large\frac{\pi}{4}: $$ \sin 2x \large\frac{dy}{dx}$$-y =\tan x$
class12
cbse
boardexam
2015
set-1
sec-c
math
modelpaper
asked
Mar 23, 2015
by
meena.p
1
answer
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