Class 10 Science Chapter 12 MCQ

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

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.

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

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

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

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

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 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.

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

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.

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

Nichrome does not undergo oxidation or burn easily even at high temperature. Due to this nichrome wire can be kept red hot without burning or breaking in air.

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.

In series circuit, the appliances do not get the same voltage as that of the power supply line because the voltage is shared by all the appliances. The appliances get less voltage and hence do not work properly. For example, all the bulbs connected in series do not get the same voltage of 220 volts of the power supply line. They get less voltage and hence glow less brightly.

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

This is so because in a parallel circuit, if one device fails, it does not affect the working of the other devices.

Resistance, R=ρlA Length, l = 300 m Cross-section area, A = 1.0 mm2 = 10-6 m2 Resistivity, ρ = 1.0 × 10−7 Ωm Resistance, R=10−7×30010−6 R = 30 Ω

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.