Physics - in Hindi

View in English View in Hindi

The number of images of an object placed between two mirrors inclined at an angle of 45o are:?


एक वस्तु 45o कोण पर झुके हुए दो दर्पणों के बीच रखी हैं इस वस्तु के कितने प्रतिबिंब होगें ??

A)
5

B)
6

C)
7

D)
8


Correct Answer :

7


Explanation :

If two plane mirrors are inclined at angle x, then the number of images formed in them is given by the formula:

Number of images formed = ( 360° /x ) - 1

By substituting the different values of angles between two inclined mirrors we can tabulate the number of images formed as follows:

Angle between the two mirrors Number of images formed
45° 7
60° 5
90° 3
120° 2
180° 1
Infinite

A steel wire has a magnetic movement M. If the wire is bend into semicircular arc, The new magnetic movement becomes?


एक स्टील के तार में एक चुंबकीय आधुर्ण M है। यदि तार अर्धवृत्ताकार चाप में मोड़ दिया जाता है, तो नया चुंबकीय आधुर्ण होगा?

A)
M

B)
2M

C)
2πM

D)
(2/π)*M


Correct Answer :

(2/π)*M


Explanation :


Let 2L = length of the bar magnet , then
magnetic moment,M = m * 2L

After bent into semicircle
πR = 2L (as circumference of a semi-circle = πR + 2*R )
R = 2L / π

When the magnet is bent in the form of a semicircle, the distance between the poles = 2R = 2 * (2L / π)

New magnetic moment = m * 2 * (2L / π) = 2M / π

The surface of a spherical shell is uniformly charged. Then what is the electric field inside the spherical shell?


एक गोलाकार खोल की सतह समान रूप से आवेशित है। फिर गोलाकार खोल के अंदर विद्युत क्षेत्र क्या है?

A)
Zero
/
शून्य

B)
constant
/
स्थिर

C)
Infinite
/
अनंत

D)
Proportional to the distance from the center
/
केंद्र से दूरी के समानुपाती


Correct Answer :

Zero


Explanation :

According to Gauss law all charges are distributed on the surface of the spherical shell. Therefore there will be no electric flux inside the spherical shell,So that the electric field inside the shell will be zero.

A wire of resistance R is stretched to reduce its diameter to half of its original value, The new resistance is?


प्रतिरोध R का एक तार इस तरह से खींचा कि इसका व्यास उसके प्रारंभिक मान से आधा हो गया है, नया प्रतिरोध होगा?

A)
2R

B)
4R

C)
8R

D)
16R


Correct Answer :

16R


Explanation :

The resistance R of a uniform cylinder of length L, of cross-sectional area A, and made of a material with resistivity ρ

R = ρL/A

New radius = r/2
New area = pi *(r/2)*(r/2)=1/4 of original area

As volume = length * area
new length = 4 * original length

New resistance R1 = ρ 4L/(A/4) = ρ 16*L/A = 16 R

The resistivity of the material depends on?


पदार्थ की प्रतिरोधकता निर्भर करती है?

A)
Length of the wire
/
तार की लंबाई

B)
Diameter of the wire
/
तार के व्यास

C)
Temperature of the wire
/
तार के तापमान पर

D)
Material of the wire
/
तार के पदार्थ पर


Correct Answer :

Material of the wire


Explanation :

The resistance R of a uniform cylinder of length L, of cross-sectional area A, and made of a material with resistivity ρ

Resistance R = ρL/A

The resistivity of a material depends on its nature and the temperature of the conductor, but not on its shape and size. A good conductor has less resistivity, whereas a bad conductor or insulator has high resistivity.
The unit for resistivity is the ohm-metre.

Calculate the energy equivalent of 1g of substance ?


1g पदार्थ के बराबर ऊर्जा की गणना करें?

A)
3*1013 J

B)
6*1013 J

C)
9*1013 J

D)
2*1013 J


Correct Answer :

9*1013 J


Explanation :

As per Einstein's equation E=mc2, where c is the speed of light (~3x108 m/s), m is the mass, and E is amount of energy.
1 g = 0.001 kg

E=0.001kg * (3 * 108 m/s)2
E=0.001 * 9 * 1016 kg*m2/s2
E=9 * 1013 kg*m2/s2

A kg*m2/s2 is a joule that measures energy

The unit of Thermal Conductivity of a material is?


किसी पदार्थ की ऊष्मीय चालकता की इकाई है?

A)

W / mK


B)

W / m2K


C)

Wm / K


D)

W2K / m



Correct Answer :

W / mK


Explanation :

In SI units, thermal conductivity is measured in watts per meter-kelvin (W / mK).

The most common element used in manufacturing of transistor is?


ट्रांजिस्टर के निर्माण में प्रयुक्त सबसे आम तत्व है?

A)

Silicon


B)

Phosphorus


C)

Gallium


D)

Germanium



Correct Answer :

Silicon


Explanation :

Transistor, three-terminal, solid-state electronic device used for amplification and switching.

The first transistors were made from germanium, but now most transistors are made from silicon. Silicon (Si) and germanium (Ge) form similar crystal structures with similar physical properties, but silicon is preferred over germanium because of silicon's superior thermal characteristics.

A larger force on a rotating body results in larger?


घूर्णन करने वाली वस्तु पर लगाये गये एक बड़े बल का परिणाम बड़े .................में होता है?

A)

mass


B)

torque


C)

axis of rotation


D)

centre of mass



Correct Answer :

torque

What is the unit of the physical quantity, magnetic flux density?


भौतिक मात्रा, चुंबकीय प्रवाह घनत्व की इकाई क्या है?

A)

Siemens


B)

Weber


C)

Henry


D)

Tesla



Correct Answer :

Tesla


Explanation :

The tesla (symbol T) is a derived unit of the magnetic induction (also, magnetic flux density) in the International System of Units. One tesla is equal to one weberper square metre.

Latest Updates

General Knowledge of MP

Under the Madhya Pradesh Ladli Laxmi Yojana, the beneficiary is paid the total amount on attaining the age of ?

Indian Politics

Who appoints the Chairman and the Members of the Union Public Service Commission?

General Knowledge of World

Which country will host the 2022 Football World Cup?

Area

The angles of a triangle are in the ratio 2 : 4 : 3. The smallest angle of the triangle is?

Which one of the following triples does not represent the sides of a triangle?

If the perimeter of a rectangle is 10 cm and the area is 4 cm2, then its length is?

Height and Distance

An aeroplane flying at a height of 300 m above the ground passes vertically above another plane at an instant when the angles of elevation of the two planes from the same point on the ground are 60º and 45º respectively. What is the height of the lower plane from the ground?

From the top of a building 90 m high, the angles of depression of the top and the bottom of a tree are 30º and 45º respectively. What is the height of the tree?

Trigonometry

What is the value of sinx √( 1 /1+cosx + 1 /1-cosx ) ?

What is cos4 A - sin4 A / cos2 A - sin2 A equal to?

If 7sin2 x +3cos2 x = 4, 0 < x < 90º ,then what is the value of tan x?

If x = a cosθ + b sinθ and y = a sinθ - b cosθ then what is x2 + y2 equal to?

Average

The mean of 5 numbers is 15. If one more number is included, the mean of the 6 numbers becomes 17. What is the included number?

The mean marks obtained by 300 students in a subject are 60. The mean of top 100 students was found to be 80 and the mean of last 100 students was found to be 50. The mean marks of the remaining 100 students are?

In an asymmetrical distribution, of the mean and median of the distribution are 270 and 220 respectively, then the mode of the data is?

Let a, b, c, d, e, f, g be consecutive even numbers and j, k, l, m, n be consecutive odd numbers. What is the average of all the numbers?

Alligation or Mixture

25 kg of alloy X is mixed with 125 kg of alloy Y. If the amount of lead and tin in the alloy X is the ratio 1 : 2 and the amount of lead and tin in the alloy Y is in the ratio 2 : 3, then what is the ratio of lead to tin in the mixture?

Simplification

The ratio of two numbers is 1 : 5 and their product is 320. What is the difference between the square of these two numbers?