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Question & Answer Forum

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Priyanshu answered 1 year(s) , 8 month(s) ago

what is the derivation of mirror formula of concave and convex mirror?

Consider the shown figure where O is a point object and I is corresponding image.
CB is normal to the mirror at B.
By laws of reflection,

For small aperture...

Asked by Chayanika

Nov 16

  • 6 Answers
  • 29 Likes
  • 109139 Views
Syeda answered 1 year(s) , 10 month(s) ago

An electric bulb is rated 220V and 100W. when it is operated on 110V, what will be the power consumed?

P = V 2/R  
If V = 220 V we have

100 W = 220 2/R
R = 220 2/100 Ω = 484 Ω. This is the resistance of the bulb.

When V = 110 V,...

Asked by Sabu

Jun 24

  • 2 Answers
  • 6 Likes
  • 102627 Views
Anand answered 1 year(s) , 2 month(s) ago

What is the difference between a virtual image and a real image?

The following are the main differences between a real image and virtual image. 

1.A real image can be caught on a screen whereas a virtual image cannot be caught on a screen.
2. A real i...

Asked by Nidhi

Dec 3

  • 15 Answers
  • 23 Likes
  • 83224 Views
Priyanshu answered 1 year(s) , 4 month(s) ago

what is the uses of convex lens in daily life

Uses of convex lens are:
1) Convex lens is used in microscopes and magnifying glasses to subject all the light to a specific point.
2) Convex lens is used as a camera lens in cameras as they foc...

Asked by Unmukt

Jan 19

  • 6 Answers
  • 10 Likes
  • 71698 Views
Priyanshu answered 1 year(s) , 9 month(s) ago

I want all the formulas used in chapter electricity

The formulas used in class X are-
1- I,current=Q,charge/T,time
2- V,potential differnce=W,work done/Q,charge
3-V,potential difference=I,current*R,resistance
4-Resisitivity=(R,res...

Asked by Prateek

Jul 9

  • 2 Answers
  • 4 Likes
  • 55611 Views
Syeda answered 1 year(s) , 10 month(s) ago

The absolute refractive indices of glass and water are 4/3 & 3/2, respectively. If speed of light in glass is 2x108 m/s , calculate the speed of light in vacum and water.( 2015 Boards Que. )

Actually, n g = 3/2 and n w = 4/3.

Absolute Refractive Index of a medium = Speed of light in vacuum/Speed of light in the medium

Speed of light in glass =...

  • 3 Answers
  • 4 Likes
  • 49318 Views
Syeda answered 1 year(s) , 10 month(s) ago

What is resistivity?

Answer.

The resistivity of a material is the resistance of a wire of that material of unit length and unit cross-sectional area. The unit for resistivity is the ohm-metre.

The resistivi

...

Asked by Devansh

Mar 22

  • 2 Answers
  • 3 Likes
  • 44418 Views
Syeda answered 1 year(s) , 9 month(s) ago

State Joule’s law of heating. Mention SI unit Heat energy.

SI Unit of Heat Energy is Joule(J)

Asked by Letusknowwhy

Apr 22

  • 4 Answers
  • 5 Likes
  • 41838 Views
Syeda answered 1 year(s) , 9 month(s) ago

If the speed of light in vacuum is 3x10⁸ m/s, find the speed of light in a medium of absolute refractive index 1.5.

Refractive index of a medium = Speed of light in vacuum/Speed of light in a medium

1.5 = 3 x 10 8 / Speed of light in medium

Speed of light in the medium = 3 x 10...

Asked by V.m.hameed

Jan 28

  • 2 Answers
  • 3 Likes
  • 40703 Views
Amarnathreddy answered 4 year(s) , 8 month(s) ago

Calculate the number of electron constituting 1 coulomb of charge

Answer: The charge on an electron is negative and it is -1.6⨯10 -19 coulomb therefore, 1 C charge is carried by 1/ (-1.6⨯10 -19) = 6.25 ⨯ 10 18 electrons. He...

Asked by Adhavan

Jul 22

  • 2 Answers
  • 3 Likes
  • 39141 Views
Syeda answered 1 year(s) , 10 month(s) ago

what are the factors on which the resistance of a conductor depends? what happens to the resistivity of a conductor when its length is doubled?

Answer.

Resistance of a conductor directly depends upon Length of the wire L
Inversely depends upon Area of Cross section of the conductor 1/A
Nature of material used.
Therefore, R

...

Asked by Inu

Jul 20

  • 11 Answers
  • 3 Likes
  • 38292 Views
Janhavi answered 4 year(s) , 1 month(s) ago

If the image formed by a mirror for all positions of the object placed in front of it is always erect and diminished, what type of mirror is it ? Draw a ray diagram to justify your answer. Where and why do we generally use this type of mirror?

A convex mirror forms an erect diminished virtual image for all the positions of the object placed in front of it.

A convex mirror is used as rear view mirrors in automobiles...

  • 2 Answers
  • 3 Likes
  • 36080 Views
Syeda answered 1 year(s) , 10 month(s) ago

8. What is the resistance of an ideal voltmeter and ammeter ? how are they connected in a circuit?

Answer .

The internal resistance of an ideal voltmeter is infinity and the internal resistance of an ideal ammeter is zero.
Ammeter is connected in series and voltmeter is connec...

Asked by R murali

Jun 6

  • 2 Answers
  • 2 Likes
  • 32165 Views
Amarnathreddy answered 4 year(s) ago

Prove F = ma

Derivation of Newton’s Second Law of Motion

Newton’s second law of motion states that the rate of change of momentum of an object is Proportional to the applied unbalanced force...

Asked by Devansh

Mar 17

  • 1 Answer
  • 5 Likes
  • 31099 Views
Syeda answered 1 year(s) , 10 month(s) ago

why does the ray passing through the centre of curvature of a concave mirror retraces it's path.

Answer: 



A ray of light passing through the centre of curvature of a concave mirror retraces its path (gets reflected along the same path), because as the ray of light passes throu

...

Asked by Venkatesh

Nov 21

  • 2 Answers
  • 0 Like
  • 30606 Views
Syeda answered 1 year(s) , 10 month(s) ago

What is meant by power of a lens ? Name and define its S.I. unit.

The ability of a lens to converge/diverge a beam of light rays is expressed in terms of its Power( P).
P=1/f
The SI unit of power of lens is Dioptre.It is den...

Asked by Sabu

Mar 8

  • 2 Answers
  • 3 Likes
  • 30506 Views
Agam answered 1 year(s) ago

An object 5 cm in size is placed at a distance of 20 cm from the concave mirror of focal length 15 cm. At what distance from the mirror should..

Object-size, h = + 5.0 cm;
Object-distance, u = – 20.0 cm;
Focal length, f = –15.0 cm;
Image-distance, v = ?
Image-size, h′ = ?
Mirror formula is             (1/v) + (1/u...

Asked by David

Dec 5

  • 2 Answers
  • 2 Likes
  • 29665 Views
Agam answered 1 year(s) , 7 month(s) ago

twinkling of stars

The phenomenon that causes stars to twinkle is atmospheric refraction. That is, the air above us is a big ocean of not very dense fluid that has a small bending effect on light that passes through it. If it wer...

Asked by Santosh

Feb 24

  • 3 Answers
  • 3 Likes
  • 28545 Views
Sharathchandar answered 3 year(s) , 8 month(s) ago

Why an ammeter is connected in series while a voltmeter is in parallel?

 (i) The internal resistance of the ammeter is very low.If we connect it in series, then          
     the maximum current can flow through it. So the accurate current should be
     measured. I...

  • 4 Answers
  • 1 Like
  • 27974 Views
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