Tag: charging and discharging

Questions Related to charging and discharging

In the thunderstorm, the charges accumulate near the upper edges of clouds are

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

  1. negatively charged

  2. positively charged

  3. neutral

  4. none of these

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Correct Option: B
Explanation:

We have to find the nature of charges on upper edges of clouds in a thunderstorm, the air currents move upwards while the water droplets move downward. This vigorous movement causes separation of charges. This leads to the positive charges collected near the upper edges of clouds and the negative charges to accumulate near the lower edges of the clouds.

The safety fuse should have

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

  1. high resistance and high melting point

  2. high resistance and low melting point

  3. low resistance and high melting point

  4. low resistance and low melting point

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Correct Option: B
Explanation:

The safety fuse should have high resistance and low melting point.


Option B is correct.

Charge 1 attracts Charge 2, Charge 2 repels Charge 3, and Charge 3 attracts Charge 4. Which of the following option must hold good for the given condition of four point charges? 

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

  1. Charge 1 attracts Charge 4

  2. Charge 2 attracts Charge 3

  3. Charge 1 repels Charge 3

  4. Charge 2 repels Charge 4

  5. Charge 1 repels Charge 4

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Correct Option: E
Explanation:

If charge 1 is positive and charge 2 is negative, then charge 1 and 2  will attract. As charge 2 and 3 repels so charge 3 should be negative. Since charge 3 and 4 attracts so charge 4 should be positive. Thus, charge 1 and 4 both are same charge so they will repel. If you take charge 1 is negative and 2 is positive similarly you get 4 is negative so 1 and 4 both have same charge. 


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

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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

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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.

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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. $5500 V/m$

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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.

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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