Why are alloys used for making standard resistance coils?

Standard resistance coils are formed from alloys having a high resistivity value and a low-temperature coefficient of resistivity.

  • The temperature coefficient of resistivity of a resistance coil should be modest. That means the resistance of certain materials will not change a lot with a change in the temperature.
  • If the resistivity of a material is high, its resistance increases. Therefore, high resistivity materials should be used to make a resistance coil for more standard resistance.
  • Alloys like manganin and constantan are examples of materials with high resistivity, a modest temperature coefficient. They are largely unaffected by environmental influences such as air, temperature, and moisture.
  • Therefore, alloys are used to produce conventional resistance coils.

Related Questions

  1. What is inductive resistance formula?
  2. In A Graph Between Current I And Voltage V, Find The Portion Corresponding To Negative Resistance.
  3. If R, C And L Are Fundamental Quantities In A Circuit Like Resistance, Capacitance And Inductance In W, Then Find Dimensional Formula For Resistance And Capacitance.
  4. Two Identical Resistors With Resistances 15 Ohm Are Connected In Series And Parallel To A Battery Of 6 V. Calculate Ratio Of Power Consumed.
  5. From the graph between current i and voltage v shown below, identify the portion corresponding to negative resistance.
  6. For The Resistor Combination, Find The Equivalent Resistance Between M and N.
  7. Three Incandescent Bulbs (Each 100 W) Are Attached In Series. In Another Circuit, Three More Bulbs Of Same Wattage Are Attached Parallelly To An Equal Source.
  8. A Closed Coil Has 500 Turns Across Rectangular Frame Of Area 4.0 Cm2 With Resistance Of 500 Ohms. The Coil Is Plane Perpendicular To A Uniform Magnetic Field Of 0.2wb/M2. Find Amount Of Charge Through Coil If Turned Over (180 Degrees Rotation).
  9. A Circuit Consists Of A Battery Of 3 Cells (2 V Each), A Combination Of Three Resistors, 10 Ohm, 20 Ohm And 30 Ohm, Attached Parallelly, With Plug Key And Ammeter (In Series).
  10. A uniform magnetic field B exists in a cylindrical region of radius 10cm as shown in figure. A uniform wire of length 80cm and resistance 4.0Ω is bent into a square frame and is placed with one side along a diameter of the cylindrical region. If the magnetic field increases at a constant rate of 0.010T/s, find the current induced in the frame.

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CBSE CLASS XII Related Questions

  • 1.
    A light copper ring is freely suspended by a light string. A bar magnet is held horizontally with its length along the axis of the ring. The magnet is moved towards the ring with its N pole facing the loop. What will happen to the ring and its position? Explain.


      • 2.
        Draw the number of scattered particles versus the scattering angle graph for scattering of alpha particles by a thin foil. Write two important conclusions that can be drawn from this plot.


          • 3.
            Four independent waves are expressed as \[ (i)\; y_1=A_1\sin\omega t, \] \[ (ii)\; y_2=A_2\sin 2\omega t, \] \[ (iii)\; y_3=A_3\cos\omega t, \] \[ (iv)\; y_4=A_4\sin\left(\omega t+\frac{\pi}{3}\right) \] The interference between two of these waves is possible in

              • (i) and (iii) only
              • (iii) and (iv) only
              • (i), (iii) and (iv) only
              • All of them

            • 4.
              If Bohr’s quantization postulate (angular momentum \( = \frac{nh}{2\pi} \)) is a basic law of nature, it should be equally valid for the case of planetary motion also. Why, then, do we never speak of quantization of orbits of planets around the Sun? Explain.


                • 5.
                  Two small identical metallic balls having charges \( q \) and \( -2q \) are kept far at a separation \( r \). They are brought in contact and then separated at distance \( \frac{r}{2} \). Compared to the initial force \( F \), they will now:

                    • attract with a force \( \frac{F}{2} \)
                    • repel with a force \( \frac{F}{2} \)
                    • repel with a force \( F \)
                    • attract with a force \( F \)

                  • 6.
                    Assertion (A) : All atoms have a net magnetic moment. Reason (R) : A current loop does not always behave as a magnetic dipole.

                      • Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
                      • Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
                      • Assertion (A) is true, but Reason (R) is false.
                      • Both Assertion (A) and Reason (R) are false.
                    CBSE CLASS XII Previous Year Papers

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