Class 10 Science Chapter 11 MCQ

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.

Power = 1 Kw, In Watt, P= 1000 W Voltage, V = 220 V Current, I = ? Current is given by I = P/V I= 1000/220 I = 4.5 A So, A fuse wire of rating slightly greater than 4.5A must be used i.e. 5A.

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

Given resistors, R1 = 2 Ω and R2 = 4 Ω Voltage, V = 6 V1 Time, t = 5 s Resistance, R = 4 Ω Heat dissipated, H = ? Resistor, Rs = R1 + R2 = 2 + 4 = 6 Ω Current, I = V/R = 6/6 = 1A. Heat dissipated H = I¬^2 Rt = 1 x 4x 5 = 20 J

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

Current is measured by an instrument called ammeter. The ammeter is always connected in series with the circuit in which the current is to be measured.

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].

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

In first case, Resistivity of the conductor, ƿ = RA¹/ l In second case, Resistivity of the conductor, ƿ = RA¹/ 2l Therefore, for same material, resistivity of the conductor will be same. So, on substituting the value of ƿ in Eq. (ii), we have RA/I = RA¹/2I = A¹ =2A

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.

The heating element of electric iron is made of nichrome wire which is a resistor. The electric wires are made of copper which is a good conductor but their covering is made of plastic which is an example of insulator.

The maximum resistance is obtained when resistors are connected in parallel combination. This equivalent resistance will be: Rs = n x R = 5 X 1/5 = 1Ω Rs = equivalent resistance for series combination.

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.

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.

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.

Kilowatt-hour is the commercial unit of electrical energy.

Energy transferred, E = power x time = 100 W x 60 s = 6000 J

Electrical energy transferred per second, E = V x I x t = 6 V × 0.5 A × 1s = 3 J/s

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.