Class 10 Science Chapter 12 MCQ

Here, all these statements are correct. Hence, your answer will be option [D].

Explanation: Electric power is given by P = Voltage x Current SI unit of voltage = volt SI unit of current = Ampere So, its unit is volt ampere.

The SI unit of electric charge coulomb is equivalent to the charge contained in 6.25 x 10 to the power 18.

In series combination of resistances same current flows through each resistor where as in parallel combination same voltage exist across each resistor. Thus, the two resistors of resistances 2 Ω and 4 Ω are connected in series has same current flowing through it.

In static electricity, the electric charges remain at rest or stationary, they do not move. The charge acquired by a glass rod rubbed with silk cloth and the charge acquired by an ebonite rod rubbed with woolen cloth are example of static electricity.

Resistivity depends on the nature of the material and the temperature but does not depend on the shape of the resistor.

Here, all these statements are correct. Hence, your answer will be option [D].

Power is given by, P = I²R P1 = I²R And, P2 = (2I)², R = 4I²R, When current is increased by 100% [It means that current becomes doubled i.e. 2I] Therefore, Increase in power dissipated = P2 – P1 = 4I²R – I²R Change in dissipated power = 3I^2R Increase in percent of power dissipated = 3P1/P1 ×100 = 300%

The current is directly proportional to the potential difference applied across the ends of a conductor it means that if the potential difference across the ends of a conductor is doubled, the current flowing through it also gets doubled, and if the potential difference is halved the current also gets halved.

As we know that: W= charge × potential difference W= Q × V As we know that Q= I × t Therefore, putting in above equation W= I × t × V V= Work done/ Current × time

The minimum resistance is obtained when resistors are connected in parallel combination. This equivalent resistance will be: Rƿ = R/n = 1/5/5 = 1/25 Ω Rƿ = equivalent resistance for parallel combination.

Given, Current, I = 1 A Time, t = 16 seconds No. of electrons, N = ? We know that, Current, I = Q/t = ne/t [e = charge of an electron = 1.6x 10 to the power -19 C and Q = ne] N= It/e = 1 x 16/ 1.6 x 10 to the power -19 = 10 to the power 20

We know that a thick wire has a greater area of cross section; whereas a thin wire has a smaller area of cross section. This means that a thick wire has less resistance and a thin wire has more resistance.

Electrical resistivity of a given metallic wire depends on number density of free electrons in the conductor which is the nature of material. It also depends on the temperature of conductor.

If we take a lot of copper metal 1 metre long and 1 square metre in area of cross section then its resistance will be 1.69 x 10 to the power -8.

We know that, H = I²Rt It shows that the heat produced is proportional to the square of the current.

An electric fuse works on the heating effect of current.

Here, all these statements are correct. Hence, your answer will be option [D].

This is so because in this case, the resistance of the wire will be low.

The power in watts is found by multiplying the potential difference in volts by the current in amperes. We can write down the above formula for electric power in words as: Electric power = Potential difference x Current

A power rating of 100 W on the bulb means that it will consume electrical energy at the rate of 100 joules per second. If we know the power P and voltage V of an electrical appliance, then we can very easily find out the current I drawn by it. This can be done by using the formula: P = V x I

Current drawn by the kettle, I = PV=3000230 =13 A So, the cable should be able to carry more current than this and hence the answer is 15 A.

If the resistance wire is cut into five pieces, the resistance of each wire is R/5. If we connect the pieces in parallel, we will get the net resistance as R/25. Therefore, the ratio will be 25.

Ohm’s law gives the relationship between current and potential difference

Since the charge of an electron is 1.6×10−19C, 6.25 × 10 to the power 18 electrons taken together constitute (6.25 × 10 to the power 18 × 1.6 × 10−19 C) or 1 coulomb of charge.