13. Electrostatics

According to the equation of capacitance of a capacitor, capacitance is numerically equal to the ratio between the charge stored on one of its plates and the potential difference between its plates. Does its value depend on the amount of charge and potential difference?

The capacitance of a capacitor, according to the equation C=Q/V, where C is the capacitance, Q is the charge stored on one of its plates, and V is the potential difference between the plates, does not depend on the amount of charge Q or the potential difference V. Instead, capacitance is a property of the capacitor … Read more

Why is it dangerous for construction workers to hold a long steel pole upright during lightning weather conditions?

It’s dangerous for construction workers to hold a long steel pole upright during lightning because steel is an excellent conductor of electricity. If lightning strikes, the metal pole would act as a direct path for the electrical current to travel through the worker’s body. This could result in severe injuries or death due to electrical … Read more

The force between two point charges is 10N. If their charge is doubled and the distance between them is reduced to half, what will be the magnitude of the force between them?

The force between two point charges is given by Coulomb’s Law: F=k.q1q2/r2​​ where: F is the force between the charges, k is Coulomb’s constant, q1 and q2​ are the magnitudes of the charges, and r is the distance between them. Now, in this case, both charges are doubled (q1′=2q1 and q2′=2q2​), and the distance between them is halved … Read more

A 100C charged body of mass 20 kg repels a 1C charged body of 10 g with a force of 2000N. Will the smaller charged body apply the same, smaller, or greater force on the 20 kg charged body?

According to Newton’s Third Law of Motion, every action has an equal and opposite reaction. This means that the force the smaller charged body applies on the 20 kg charged body will be the same as the force the 20 kg charged body applies on the smaller body, but in the opposite direction. So, even … Read more

Take two oppositely charged rods, place them separately near small pieces of paper. Why do they both attract small pieces of paper? Is there any third type of charge on papers which attracts both positive and negative charges?

The pieces of paper are initially neutral. When a charged rod is brought near, it induces a charge separation in the paper—one side becomes slightly positive and the other slightly negative. Since opposite charges attract, the paper gets attracted to both positively and negatively charged rods. There is no third type of charge; it’s just … Read more

You take your car to a service station to get it polished. After a while, you observe that your car attracts dust. Why is dust attracted to the car?

When the car is polished, friction between the polishing cloth and the car’s surface can cause static charge buildup. This creates an electric field around the car, which attracts dust particles because they are either neutral or oppositely charged.   Related Questions: Rub a plastic ruler with your hair. Place it near running water from … Read more

Two identical spheres have the same masses. Then we charge both of them so they are oppositely charged. After charging, will both bodies have the same mass or different masses? Explain.

The masses will be slightly different. The sphere that gains electrons will have a slightly higher mass because electrons have a small mass. The sphere that loses electrons will have a slightly lower mass. However, the difference in mass is extremely small and usually negligible.   Related Questions: Rub a plastic ruler with your hair. … Read more

Rub a plastic ruler with your hair. Place it near running water from a tap. You see that the thin stream of water is deflected. Explain why.

When the plastic ruler is rubbed with hair, it gains a charge due to friction (electrostatic charging). Water molecules are polar, meaning they have positive and negative sides. The charged ruler attracts the oppositely charged ends of the water molecules, causing the stream of water to bend toward the ruler. Related Questions: Numerical Problems of … Read more