Ikesh

Ashok0210

Asked: February 23, 2021In: Class 12 Physics

What conclusion can you draw from the following observations on a resistor made of alloy manganin?

Class 12 Physics CBSE and UP Board Current Electricity Additional Exercise Chapter-3 Exercise 3.17 NCERT Solutions Class 12 Physics Chapter 3 Question 17

Ashok0210

Asked: February 23, 2021In: Class 12 Physics

Two wires of equal length, one of aluminum and the other of copper have the same resistance. Which of the two wires is lighter? Hence explain why aluminum wires are preferred for overhead power cables. (ρAl = 2.63 × 10⁻⁸ Ω m, ρCu = 1.72 × 10⁻⁸Ω m, Relative density of Al = 2.7, of Cu = 8.9.)

Class 12 Physics CBSE and UP Board Current Electricity Additional Exercise Chapter-3 Exercise 3.16 NCERT Solutions Class 12 Physics Chapter 3 Question 16

Ashok0210

Asked: February 23, 2021In: Class 12 Physics

(a) Six lead-acid type of secondary cells each of emf 2.0 V and internal resistance 0.015 Ω are joined in series to provide a supply to a resistance of 8.5 Ω. What are the current drawn from the supply and its terminal voltage? (b) A secondary cell after long use has an emf of 1.9 V and a large internal resistance of 380 Ω. What maximum current can be drawn from the cell? Could the cell drive the starting motor of a car?

Class 12 Physics CBSE and UP Board Current Electricity Additional Exercise Chapter-3 Exercise 3.15 NCERT Solutions Class 12 Physics Chapter 3 Question 15

Ashok0210

Asked: February 23, 2021In: Class 12 Physics

The earth’s surface has a negative surface charge density of 10⁻⁹ C m⁻². The potential difference of 400 kV between the top of the atmosphere and the surface results (due to the low conductivity of the lower atmosphere) in a current of only 1800 A over the entire globe. If there were no mechanism of sustaining atmospheric electric field, how much time (roughly) would be required to neutralise the earth’s surface? (This never happens in practice because there is a mechanism to replenish electric charges, namely the continual thunderstorms and lightning in different parts of the globe). (Radius of earth = 6.37 × 10⁶ m.)

Class 12 Physics CBSE and UP Board Current Electricity Additional Exercise Chapter-3 Exercise 3.14 NCERT Solutions Class 12 Physics Chapter 3 Question 14

Ashok0210

Asked: February 23, 2021In: Class 12 Physics

A magnetic field of 100 G (1 G = 10⁻⁴ T) is required which is uniform in a region of linear dimension about 10 cm and area of cross-section about 10⁻³ m² . The maximum current-carrying capacity of a given coil of wire is 15 A and the number of turns per unit length that can be wound round a core is at most 1000 turns m⁻¹. Suggest some appropriate design particulars of a solenoid for the required purpose. Assume the core is not ferromagnetic.

Class 12 Physics CBSE and UP Board Moving Charges and Magnetism Chapter-4 Exercise 4.15 Additional Exercise NCERT Solutions Class 12 Physics Chapter 4 Question 15

Ashok0210

Asked: February 23, 2021In: Class 12 Physics

Two concentric circular coils X and Y of radii 16 cm and 10 cm, respectively, lie in the same vertical plane containing the north to south direction. Coil X has 20 turns and carries a current of 16 A; coil Y has 25 turns and carries a current of 18 A. The sense of the current in X is anticlockwise, and clockwise in Y, for an observer looking at the coils facing west. Give the magnitude and direction of the net magnetic field due to the coils at their centre.

Class 12 Physics CBSE and UP Board Moving Charges and Magnetism Chapter-4 Exercise 4.14 Additional Exercise NCERT Solutions Class 12 Physics Chapter 4 Question 14

Ashok0210

Asked: February 23, 2021In: Class 12 Physics

(a) A circular coil of 30 turns and radius 8.0 cm carrying a current of 6.0 A is suspended vertically in a uniform horizontal magnetic field of magnitude 1.0 T. The field lines make an angle of 60º with the normal of the coil. Calculate the magnitude of the counter torque that must be applied to prevent the coil from turning. (b) Would your answer change, if the circular coil in (a) were replaced by a planar coil of some irregular shape that encloses the same area? (All other particulars are also unaltered.)

Class 12 Physics CBSE and UP Board Moving Charges and Magnetism Chapter-4 Exercise 4.13 NCERT Solutions Class 12 Physics Chapter 4 Question 13

Ashok0210

Asked: February 23, 2021In: Class 12 Physics

In Exercise 4.11 obtain the frequency of revolution of the electron in its circular orbit. Does the answer depend on the speed of the electron? Explain.

Class 12 Physics CBSE and UP Board Moving Charges and Magnetism Chapter-4 Exercise 4.12 NCERT Solutions Class 12 Physics Chapter 4 Question 12

Ashok0210

Asked: February 23, 2021In: Class 12 Physics

In a chamber, a uniform magnetic field of 6.5 G (1 G = 10⁻⁴ T) is maintained. An electron is shot into the field with a speed of 4.8 × 10⁶ m s⁻¹ normal to the field. Explain why the path of the electron is a circle. Determine the radius of the circular orbit. (e = 1.6 × 10⁻¹⁹ C, me = 9.1×10⁻³¹ kg)

Class 12 Physics CBSE and UP Board Moving Charges and Magnetism Chapter-4 Exercise 4.11 NCERT Solutions Class 12 Physics Chapter 4 Question 11

Ashok0210

Asked: February 23, 2021In: Class 12 Physics

Two moving coil meters, M₁ and M₂ have the following particulars: R₁ = 10 Ω, N₁ = 30, A₁ = 3.6 × 10⁻³m², B₁ = 0.25 T R₂ = 14 Ω, N₂ = 42, A₂ = 1.8 × 10⁻³ m² , B₂ = 0.50 T (The spring constants are identical for the two meters). Determine the ratio of (a) current sensitivity and (b) voltage sensitivity of M₂ and M₁.

Class 12 Physics CBSE and UP Board Moving Charges and Magnetism Chapter-4 Exercise 4.10 NCERT Solutions Class 12 Physics Chapter 4 Question 10

Ikesh

What conclusion can you draw from the following observations on a resistor made of alloy manganin?

In Exercise 4.11 obtain the frequency of revolution of the electron in its circular orbit. Does the answer depend on the speed of the electron? Explain.

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