Tag: electric fields

Questions Related to electric fields

State whether true or false:
Objects with the same type of charges attract each other.

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

In electrostatics-


Like charges repel each other and unlike nature of charge attract each other.

Hence objects with same type of charges repel each other.

Given statement is $False$.

Electric force can be_______

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. always attractive

  2. always repulsive

  3. attractive or repulsive

  4. None of these

Show answer
Correct Option: C
Explanation:

Electric force can be either attractive or repulsive .

Same charge repel each other while unlike nature of charge attract each other.

Answer-(C)

Two copper spheres, $A$ and $B$, are identical in all respect but A carries a charge of $-3 \mu C$ whereas $B$ Is charged to $+1 \mu C$. The two spheres are brought together until they touch and then separated by some distance. Which of the following statements is true concerning the electrostatic force $F$ between the spheres?

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. $F = 0$ as one of the spheres is uncharged

  2. $F = 0$ as both the spheres are uncharged

  3. $F$ is attractive

  4. $F$ is repulsive.

Show answer
Correct Option: D
Explanation:

Charge on $A^{+}$ sphere $=-3$ $uC$

Charge on $B$ sphere $=+1$ $uC$
When they are connected the charge get redistributed, i.e.
$\Rightarrow$ Charge on both sphere $=\dfrac{-3+1}{2}$ $uC=-1$ $uC$
So charge on either sphere $=-1$ $uC$
Therefore, After connecting charge on sphere $A=-1$ $uC$
After connecting charge on sphere $B=-1$ $uC$
Therefore, there will be a repulsive force between the sphere because of like charges.

What happens when some charge is placed on a soap bubble?

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. Its radius decreases

  2. Its radius increases

  3. The bubble collapses

  4. None of the above

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Correct Option: B
Explanation:

The radius of soap bubble increases due to inter-electronic repulsion.
Note that, the bubble may also explode if excess charge is large enough.

The potential at a point $(x, 0, 0)$ is given by $V = \left(\dfrac{1000}{x} + \dfrac{1500}{x^2} + \dfrac{500}{x^3}\right)$. The intensity of the electric field at $x = 1$ will be

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. $550 V/m$

  2. $55 V/m$

  3. $55000 V/m$

  4. $5500 V/m$

Show answer
Correct Option: D
Explanation:
$V=(\cfrac{1000}{x}+\cfrac{1500}{x^{2}}+\cfrac{500}{x^{3}})$
We know that, $E=\cfrac{-dv}{dr}$
So,
$E=\cfrac{-d(\cfrac{1000}{x}+\cfrac{1500}{x^{2}}+\cfrac{500}{x^{3}})}{dx}$   at $x=1$
$=-[\cfrac{(-1000)}{x^{2}}-\cfrac{2\times 1500}{x^{3}}-\cfrac{3\times 500}{x^{4}}] _{x=1}$
$=1000+3000+1500=5500\,V/m$

Consider two balls having same kind of charge on them. Identify the correct statement:

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. They will repel one another.

  2. They will attract one another.

  3. They might attract one another.

  4. They will not have any effect on one another.

Show answer
Correct Option: A
Explanation:

Two bodies having same nature of charge repel each other.


Answer-(A)

Five ball numbered $1$ to $5$ are suspended using separate threads. Pairs $(1,2)$, $(2,4)$ and $(4,1)$ show electrostatic attraction while pairs $(2,3)$, $(4,5)$ show repulsion. Therefore, ball $1$ must be

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. neutral

  2. metallic

  3. positively charged

  4. negatively charged

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Correct Option: A

If a comb is rubbed on dry hairs, and then brought near paper pieces, it :

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. attracts paper

  2. repels paper

  3. remains indifferent to paper

  4. either attracts or repels paper

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Correct Option: A
Explanation:

If we bring small bits of paper near a rubber (or plastic) comb, it is found that the comb does not attract the bits of paper. But if the same comb is first rubbed on dry hairs and then it is brought near the paper pieces, it attracts them.

True or False?
S1: Similar charge attracts each other.
S2: Similar charge repels each other.

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. True, True

  2. True, false

  3. False, True

  4. false, false

Show answer
Correct Option: C
Explanation:

There are 2 types of electrical charges - positive and negative - are said to be opposite types of charge. Consistent with our fundamental principle of charge interaction, a positively charged object will attract a negatively charged object. Oppositely charged objects will exert an attractive influence upon each other. In contrast to the attractive force between two objects with opposite chargess, two objects that are of like charge will repel each other. That is, a positively charged object will exert a repulsive force upon a second positively charged object. This repulsive force will push the two objects apart. Similarly, a negatively charged object will exert a repulsive force upon a second negatively charged object. Objects with like charge repel each other.
Hence, the statement is false.

State whether true or false:

Like charges attract each other.

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

Like charges repel each other whereas unlike charges attract each other.

Hence, the correct answer is option B.