Tag: physics

Questions Related to physics

Fill in the blank:

A boy blinks his right eye. Mirror image of the boy blinks its ______ eye.

physics reflection of light and shadow lateral inversion right or left reflection at plane surface

  1. both

  2. right

  3. none

  4. left

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Correct Option: D
Explanation:

Due to lateral inversion by mirror, right appears on left and left appears on right.

The image formed by a plane mirror is always ....... inverted.

physics reflection of light and shadow lateral inversion right or left reflection at plane surface

  1. laterally

  2. virtually

  3. really

  4. none

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Correct Option: A
Explanation:

The image formed by a plane mirror is always Laterally inverted.

Mark correct option.

physics reflection of light and shadow lateral inversion right or left reflection at plane surface

  1. The laws of reflection of light hold only for plane surfaces

  2. The size of virtual image can be measured by receiving it on screen

  3. Plane mirror alongs form an erect image

  4. Plane mirror may form inverted image

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Correct Option: D
Explanation:

Let solve it by each option

  1. Law of reflection of light holds good for all the mirrors irrespective of their shape and size, hence option A is false
  2.  A virtual image cannot be caught on screen so we cannot measure the size, it is also a false statement
  3. Plane mirror always forms a virtual image, hence it's a false statement
  4. Light rays  which comes from the object  get reflected from plane mirror and reaches to human eye, at this point human feel that reflected ray is coming from the mirror . This is the reason why object looks laterally inverted
  5. Hence option D is the right answer

Ohm's law in vector form is :

safety precautions to be taken while handling electricity ohm's law electric charge and electric current current electricity physics

  1. $V=I.R$

  2. $\overrightarrow { J } =\sigma \overrightarrow { E } $

  3. $\overrightarrow { J } =\rho \overrightarrow { E } $

  4. $\overrightarrow { E } =\sigma \overrightarrow { J } $

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Correct Option: B

If E and B denote electronic and magnetic field respectively, which of the following is dimensionless?

properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics

  1. $\sqrt { { \mu } _{ 0 }{ \varepsilon } _{ 0 } } \dfrac { E }{ B } $

  2. $ { { \mu } _{ 0 }{ \varepsilon } _{ 0 } } \dfrac { E }{ B } $

  3. ${ \mu } _{ 0 }{ \varepsilon } _{ 0 }{ \left( \dfrac { B }{ E } \right) }^{ 2 }$

  4. $\dfrac { E }{ { \varepsilon } _{ 0 } } \dfrac { { \mu } _{ 0 } }{ B } $

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Correct Option: A
Explanation:

We know that Velocity of light  $C _0=\dfrac{1}{\sqrt{\mu _0 \epsilon _0}}$

And also velocity of electromagnetic wave $V=\dfrac{E}{B}$
 $[C _0]=\left[\dfrac{1}{\sqrt{\mu _0 \epsilon _0}}\right]=[LT^{-1}]$

 $[V]=\left[\dfrac{E}{B}\right]=[LT^{-1}]$

$\left[\sqrt { { \mu } _{ 0 }{ \varepsilon } _{ 0 } } \dfrac { E }{ B } \right]=[LT^{-1}]^{-1}[LT^{-1}]=[M^0L^0T^0]$    (Dimention less),

Option A

Ratio of magnetic fields at 10 cm and 20 cm from a infinitely long current carrying wire is

properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics

  1. 1 : 2

  2. 1 : 4

  3. 2 : 1

  4. 4 : 1

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Correct Option: A

A large metal sheet carries an electric current along its surface. Current per unit length is $\lambda $. Magnetic field near the metal sheet is

properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics

  1. $\dfrac{\lambda { \mu } _{ 0 }}{2} $

  2. $\dfrac{\lambda { \mu } _{ 0 }}{2 \pi} $

  3. $\lambda { \mu } _{ 0 }$

  4. $ { \mu } _{ 0 }2\lambda \pi $

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Correct Option: A

A particle of charge $q$ and mass $m$ starts moving from origin under the action of an electric field $\vec { E }$=$E _ { 0 } \vec i $ and magnetic field $\vec { B }$=$B _ { 0 } \vec k $ . Its  velocity at $( x , 3,0 )$ is $( 4 i + 3 i )$ , the value of $x$ is:

properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics

  1. $\dfrac { 36 E _ { o } B _ { 0 } } { q m }$

  2. $\dfrac { 25 m } { 2 q E _ { 0 } }$

  3. $\dfrac { 10 m } { q E _ { o } }$

  4. $\dfrac { 25 E _ { 0 } B _ { 0 } } { m }$

Show answer
Correct Option: B
Explanation:

$\begin{array}{l} \left( { q{ \varepsilon _{ 0 } } } \right) x=\frac { 1 }{ 2 } m{ v^{ 2 } } \ \Rightarrow q{ \varepsilon _{ 0 } }x=\frac { { 25m } }{ 2 }  \ x=\frac { { 25 } }{ { 2q{ \varepsilon _{ 0 } } } }  \ Hence, \ option\, \, B\, \, is\, \, correct\, \, answer. \end{array}$

Pick correct statements from among the following : 
a) Electric field and magnetic field are basically independent
b) Electric field and magnetic field are to aspects of the electromagnetic field
c) Electric field and magnetic field may be produced by charge at rest
d) A moving charge produces both electric and magnetic fields

properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics

  1. a and b are correct

  2. b and d are correct

  3. b, c and d are correct

  4. a, c and d are correct

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Correct Option: B
Explanation:

Electric field and magnetic field are not independent. They are two aspects of the electromagnetic field. Charge at rest only produces electric field. Moving charge produces both electric field and magnetic field.

Two particles having the same specific change (q/m) enter a uniform magnetic field with the same speed but at angles of $30^ \circ$ and $60^\circ$ with the field. Let a, b and c be the ratios of their pitches, radii and periods of their helical paths respectively, then

properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics

  1. $abc = 1$

  2. $a + b = 2 \sqrt c$

  3. $a^2 = c$

  4. $ab = c$

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Correct Option: D