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1. 2T

2. T

3. 3/2T

4. 3T

Radioactive decay,  Where N(t) is the amount of sample which remains after time t. Given that 75% of the sample has decayed, hence the remaining will be 25% of initial,  Also  Take loge both sides and solve Option (1) is correct

What should be the angle between the axes of the polarizer, so that the intensity of the beam coming out of analyzer is 3/8 I

1. 45 degree

2. 30 degree

3. 60 degree

When unpolarized light is passed through the polarizer the intensity becomes half, Hence after passing through polarizer equals  Now after coming out of the analyzer, the intensity becomes  Use Malus Law,  Option (2) is correct.

1) Nurture

2) Nature

3) Return

4) Renter

Nature Option (2) is correct.

A potential difference of 1V is applied across the other diagonal. What will be the current in the resistor along the diagonal?

1. 0.5 A

2. 1 A

3. 5 A

4. Zero

By closely observing at the figure, you will find that this circuit is a balanced wheat stone bridge. Hence no current will pass through the diagonal. Option (4) is correct
1. The acceleration is constant both in magnitude and direction.

2. The acceleration is constant in direction but not in magnitude

3. The acceleration is constant in magnitude but not in direction

4. The acceleration is neither constant in magnitude nor in direction.

In any type of motion, Force either changes the direction of particle or magnitude or both. In a uniform circular motion, the velocity of the particle is constant and the magnitude is constant as well and it equals to $a_{c} = \frac{v^{2}}{r}$ . So the direction of the particle changes because of the force, if there was no force then the particle might have followed a straight path rather than a circular path.

So option (3) is correct.

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If the speed of the stream is v and the speed of the boat with respect to the stream is u, then which of the following gives the correct relationship between u and v

1. u=v
2. u=3v
3. v=2u
4. v=3u
Velocity of boat w.r.t stream is u  Time taken by boat to go downstream, t = d/ (u+v)  ......(1) Time taken by boat to go upstream, 2t = d/ (u-v)  .........(2) From equation (1) and (2) 2*d/ (u+v) = d/ (u-v) -> 2*(u-v) = (u+v) -> u =3v  Option (2) is correct

1) Goods

2) School

3) Bus

4) Traffic

Option (1)  "Goods" is correct. Because transaction of 2nd is done through 1st.
represents change enthalpy  And  represents the change in internal energy. According to First law of thermodynamics, H and E are related as,
testing.png Find the missing figure in the figure matrix
Just look cross
Hi, how to quicly solve DI Questions!
You will need to practise a lot
crude oil is also obtained from refinery why d is not write? Coal : Mine c) Black : Night Correct Option - Power : Physics
Engineering
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Let where       Then   equals :

• Option 1)

• Option 2)

• Option 3)

• Option 4)

Option 2

Engineering
8 Views   |

Question

From a sphere of mass M and radius R, a  smaller sphere of radius  is carved out such that the cavity made in the original sphere is between its centre and the periphery. (See figure). For the configuration in the figure where the distance between the centre of the original sphere and the removed sphere is 3R, the gravitational force between the two spheres is :

Question

From a sphere of mass M and radius R, a  smaller sphere of radius  is carved out such that the cavity made in the original sphere is between its centre and the periphery. (See figure). For the configuration in the figure where the distance between the centre of the original sphere and the removed sphere is 3R, the gravitational force between the two spheres is :

Solution : Volume of removed sphere, Volume of the sphere (remaining) Therefore mass of sphere carved and remaining sphere are at respectively 1/8M and 7/8M.Therefore, gravitational force between these two sphere,
Engineering
53 Views   |

Let ABC be a triangle whose circumcentre is at P.  If the position vectors of A, B, C

and P are

respectively, then the position vector of the orthocentre of this triangle, is :

• Option 1)

• Option 2)

• Option 3)

• Option 4)

Engineering
56 Views   |

If (10)9 + 2(11)1   (10)8 + 3(11)2  (10)7 +......  +10 (11)9 = k (10)9, then k is equal to :

• Option 1)

100

• Option 2)

110

• Option 3)

• Option 4)

Use

Sum of n terms of a GP -

$S_{n}= \left\{\begin{matrix} a\frac{\left ( r^{n}-1 \right )}{r-1}, &if \: r\neq 1 \\ n\, a, & if \, r= 1 \end{matrix}\right.$

- wherein

$a\rightarrow$ first term

$r\rightarrow$ common ratio

$n\rightarrow$ number of terms

and

(10)9 + 2(11)1 (10)8 + 3(11)2 (10)7 +......  +10 (11)9 = k(10)9

Take common 109

$10^{9}\left [ 1+2\times \frac{11}{10}+3\times \left ( \frac{11}{10} \right )^{2}+\cdot \cdot \cdot \cdot \cdot \cdot \cdot \cdot \cdot 10\times \left ( \frac{11}{10} \right ) ^{9}\right ]= k\left ( 10 \right )^{9}$

$\therefore k= 1+2x+3x^{2}+\cdot \cdot \cdot \cdot \cdot \cdot \cdot 10x^{9} \: where \:\:x=\frac{11}{10}$

$kx= x+2x^{2}+3x^{3}+\cdot \cdot \cdot \cdot \cdot \cdot \cdot \cdot \cdot 10x^{10}$

Subtract

$k-kx= 1+x+x^{2}+x^{3}+x^{4}\cdot \cdot \cdot \cdot \cdot \cdot \cdot \cdot (-10x^{10})$

$k(1-x)= \frac{1(x^{10}-1)}{x-1}-10x^{10}$

$k\left ( 1-\frac{11}{10} \right )= \frac{\left ( \frac{11}{10} \right )^{10}-1}{\frac{11}{10}-1}-10\times \left ( \frac{11}{10} \right )^{10}$

$-\frac{k}{10}= \frac{\left ( \frac{11}{10} \right )^{10}}{\frac{1}{10}}-10-\frac{11^{10}}{10^{9}}$

$\therefore k=100$

Option 1)

100

Option 2)

110

Option 3)

Option 4)

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Engineering
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In a large building, there are 15 bulbs of   40 W, 5 bulbs of 100 W, 5 fans of 80 W and 1 heater of 1 kW.  The voltage of the electric mains is 220 V.  The minimum capacity of the main fuse of the building will be :

• Option 1)

8 A

• Option 2)

10 A

• Option 3)

12 A

• Option 4)

14 A

As we have learned

In parallel Grouping -

$\frac{1}{R_{eq}}=\frac{1}{R_{1}}+\frac{1}{R_{2}}+\cdot \cdot \cdot +\frac{1}{R_{n}}$

-

Resistance of each bulb of 40 W $= \frac{v^2 }{P } = \frac{220 ^2 }{40 }= 1210 \Omega$

Resistance of 15 bulbs = 1210/15 = 242/3 $\Omega$

Resistance of 100 W bulb = $\frac{v^2 }{P }= \frac{220 ^2 }{100} = 484 \Omega$

Resistance of 5 such bulbs = 485/5 $\Omega$

Resistance of fan =  $\frac{v^2 }{P }= \frac{220 ^2 }{80}$   =  605 $\Omega$

Resistance of 5 such fan  = 605 /5 $\Omega$

= 121 $\Omega$

Resistance of heater = $\frac{220 ^2 }{1000} = 242 /5\Omega$

Equivalent resistance

$\frac{1}{R} = \frac{1}{R_1}+ \frac{1}{R_2} + \frac{1}{R_3}+ \frac{1}{R_4}\\ = \frac{3}{242} + \frac{5}{484}+ \frac{5}{605}+\frac{5}{242} \\$

$= \frac{6+5+4+10}{484} = \frac{25 }{484}$

R = 484 / 25

$I \geq \frac{V}{}R = \frac{220 }{\frac{484}{25}} = \frac{125 }{11} = 11.36 A$

$I^{min } = 12 A$

Option 1)

8 A

Option 2)

10 A

Option 3)

12 A

Option 4)

14 A

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Engineering
43 Views   |

In the circuit shown, current (in A) through the 50 V and 30 V batteries are, respectively :

• Option 1)

2.5 and 3

• Option 2)

3.5 and 2

• Option 3)

4.5 and 1

• Option 4)

3  and 2.5

As we discussed in

Cell -

The device which converts Chemical energy into electrical energy is known as electric cell.

Option 1)

2.5 and 3

Option 2)

3.5 and 2

Option 3)

4.5 and 1

Option 4)

3  and 2.5

Engineering
45 Views   |

A d.c. main supply of e.m.f. 220 V is connected across a storage battery of e.m.f. 200 V through a resistance of 1. The battery terminals are connected to an external resistance ‘R’. The minimum value of ‘R’, so that a current passes through the battery to charge it is :

• Option 1)

• Option 2)

• Option 3)

• Option 4)

zero

$r=\left ( \frac{\varepsilon -v}{v} \right )R$

$1=\left ( \frac{20}{220} \right )R$

$\Rightarrow R =11\Omega$

Option 1)

Option 2)

Option 3)

Option 4)

zero

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Engineering
111 Views   |

In the circuit shown, the current in the 1 resistor is :

• Option 1)

1.3 A ,from P to Q

• Option 2)

0 A

• Option 3)

0.13 A ,from Q to P

• Option 4)

0.13 A ,from P to Q

answer is option 3)0.13A from Q  to P

•  Let, Current i1 from 6v battery passes through 3 ohm resistance . At Q current breaks and current i2 goes through 3 ohm and ( i1-i2 ) goes through 1 ohm ,.
• Applying, kirchoffs law in 1st and 2nd loop,we get two eqns as follows
• 4i1-i2=6
• 6i2-i1=9
• solving ,,  i1-i2 =0.13 A
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Engineering
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In the electric network shown, when no current flows through the resistor in the arm EB, the potential difference between the points A and D will be :

• Option 1)

3V

• Option 2)

4V

• Option 3)

5V

• Option 4)

6V

The potential difference can be calculated via following method:

$-4+3+V_{cd}+0=0$

$V_{cd}=1 Volt$

$\therefore V_{A}-V_{D}=9-3-1=5V$

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