Home
Class 10
PHYSICS
(a) State Joule's law of heating. (b) ...

(a) State Joule's law of heating.
(b) an alloy of nickel and chromium is used as the heating element. Why ?
(c ) How does a fuse wire protect electrical appliances ?

Text Solution

Verified by Experts

`H= I^(2)RT`
Joule.s law of heating states that the heat produces in any resistor is: • Directly proportional to the square of the current passing through the resistor.
• Directly proportional to the resistance of he resistor.
• Directly proportional to the lime for which the current is passing through the resistor.
(i) It has high resistivity
(ii) It has a high melting point
(iii) It is not easily oxidized.
  The resistance decreases as the conductor is made thicker
Reason: Resistance is inversely proportional to area of cross section A. (i.e) `R  prop 1//A -here, A =pi//r^(2)`
Where, r is the radius which determines the thickness.
Promotional Banner

Topper's Solved these Questions

  • SAMPLE PAPER - 6

    FULL MARKS|Exercise PART-IV|6 Videos

  • SAMPLE PAPER - 6

    FULL MARKS|Exercise PART - II|10 Videos

  • SAMPLE PAPER - 3

    FULL MARKS|Exercise PART - IV|6 Videos

  • SAMPLE PAPER - 7

    FULL MARKS|Exercise PART - IV|6 Videos

Similar Questions

Explore conceptually related problems

(i) State Joule's law off heating. (ii) An alloy of nickel and chromium is used as the heating element. Why? (iii) How does a fuse wire protect electrical appliances?

Why nickel is used as heating element ?

(i) Define electric potential and potential difference. (ii) How does a fuse wire protect electrical appliances?

When the magnetic flux associated with a coil changes an emf is induced in the circuit. A. State Faraday's law of electromagnetic induction. B. Mention the physical significance of Len'z law with an example. C. When an electrical appliance is switched off, sparking occurs. Why?

Electric field lines are a pictorial representation of the electric field around charges. A. State Gauss's Law in Electrostatics. B. Using this law derive an expression for the electric field intensity due to a uniformly charged thin spherical shell at a point. i. Outside the shell ii. Inside the shell C. Suppose that you are in a cave deep withing the earth. Are you safe from thunder and lighting? Why?

A metal block of heat capacity 90J//.^(@)C placed in a room at 25^(@)C is heated electrically. The heater is switched off when the temperature reaches 35^(@)C . The temperature of the block rises at the rate of 2^(@)C//s just after the heater is switched on and falls at the rate of 0.2^(@)C//s just after the heater is switched off. Assume Newton's law of cooling to hold (a) Find the power of the heater. (b) Find the power radiated by the block just after the heater is switched off. (c ) Find the power radiated by the block when the temperature of the block is 30^(@)C . (d) Assuming that the power radiated at 30^(@)C respresents the average value in the heating process, find the time for which the heater was kept on.

a. Magnetic field lines show the direction (at every point) along which a small magnetised needle aligns (at the point) Do the magnetic field also represent the lines of force one a moving charged particle at every point ? b. Magnetic field lines can be entirely confined within the core of a toroid , but not within a straight solenoid. Why ? c. If magnetic monopoles existed, how would the Gauss ' law of magnetism be modified ? d. Does a bar magnet exert a torque on itself due to its own field ? Does one element of a current - carrying wire exert a force on another element of the same wire ? e.Magnetic field arises due to charges in motion . Can a system have magnetic moments eventhough its charge is zero ?

A conducting wire ab of length l, resistance r and mass m starts sliding at t = 0 down a smooth, vertical, thick pair of connected rails as shown in . A uniform magnetic field B exists in the space in a diraction perpendicular to the plane of the rails. (a) Write the induced emf in the loop at an instant t when the speed of the wire is v. (b) what would be the magnitude and direction of the induced current in the wire? (c) Find the downward acceleration of the wire at this instant. (d) After sufficient time, the wire starts moving with a constant velocity. Find this velocity v_m. (e) Find the velocity of the wire as a function of time. (f) Find the displacement of the wire as a functong of time. (g) Show that the rate of heat developed inte wire is equal to the rate at which the gravitational potential energy is decreased after steady state is reached.

A parallel - plate capacitor having plate area 20cm^2 and seperation between the plates 1.00 mm is connected to a battery of 12.0V . The plates are pulled apart to increase the separation to 2.0mm . (a ) calculate the charge flown through the circuit during the process . (b ) How much energy is absorbed by the battery during the process ? (c ) calculate the stored energy in the electric field before and after the process . (d ) Using the expression for the force between the plates , find the work done by the person polling the plates apart . (e ) Show and justify that no heat is produced during this transfer of charge as the separation is increased.