Resistance in meter bridge’s two arms are 5 ohms and R ohms. When resistance R is shunted with equal resistance, new balance point becomes 1.6l1. Calculate R.

Resistance can be defined as the measurement of opposition of current flow in an electrical circuit. Therefore, in order to determine the value of resistance (R), we need to:

  • Known resistance, R = 5Ω
  • Initial Unknown Resistance = RΩ
  • New Balancing Point, L = 1.6l1

Thus, R/L = S/100 − L … [1]

Here,

  • R = Known Resistance
  • S = Unknown Resistance

In the first stage, the balancing point is at l1.

Now, after replacing the values as:

R = 5Ω and L = l1 in equation [1], we can obtain,

⇒ 5/l1 = S/100−l1 … [2]

Now, after resistance R is shunted with equal resistance R, the resistance in that arm can be R2

Then,

⇒ 5L = R/2/100−L … [3]

Replace the value of L1 in equation 3. We can obtain,

⇒ 5/1.6l1 = R/2/100−1.6l1 … [4]

Hence, divide the given equation 2 by 4, in order to get,

1.6/2 = (100 − 1.6l1)/100 − l1

⇒ 160 − 1.6l1 = 200 − 3.2l1

⇒ 1.6l1 = 40

⇒ l1 = 401.6

= 25 cm

Replace l1=25cm in the above equation 1, we get,

5/25 = R/100 − 25

⇒ R = 15Ω


Related Questions

  1. 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.
  2. In A Graph Between Current I And Voltage V, Find The Portion Corresponding To Negative Resistance.
  3. 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).
  4. 1.0 M Rectangular Loop With A Sliding Connector Is In Uniform Magnetic Field 2t Perpendicular To Plane Of Loop. Resistance Is 2 Ohms. Two Resistances, 6 Ohms And 3 Ohms, Are Connected.
  5. 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.
  6. Two Identical Resistors With Resistances 15 Ohm Are Connected In Series And Parallel To A Battery Of 6 V. Calculate Ratio Of Power Consumed.
  7. For The Resistor Combination, Find The Equivalent Resistance Between M and N.
  8. Two Concentric Coplanar Circular Loops Of Wire (Resistance Per Unit Length 10 4 Ohms M-1) Have Diameters 0.2 M And 2 M. With Time-Varying Potential Difference Of (4+2.5t) Applied To Larger Loop, Find Current In Smaller One.
  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).

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CBSE CLASS XII Related Questions

  • 1.

    A circular coil of 100 turns and radius $\left(\frac{10}{\sqrt{\pi}}\right)$ cm carrying current of $5.0\,\text{A}$ is suspended vertically in a uniform horizontal magnetic field of $2.0\,\text{T}$. The field makes an angle $30^\circ$ with the normal to the coil. Calculate:

    (I) the magnetic dipole moment of the coil, and

    (II) the magnitude of the counter torque that must be applied to prevent the coil from turning.


      • 2.

        A ray of light MN is incident normally on the face corresponding with side AB of a prism with an isosceles right-angled triangular base ABC. Trace the path of the ray as it passes through the prism when the refractive index of the prism material is (i) $\sqrt{2}$, and (ii) $\sqrt{3}$.


          • 3.

            A rectangular loop of size 5 cm $\times$ 8 cm is lying in the $x$-$y$ plane in a uniform magnetic field $\vec{B} = (2.0\ \text{T})\hat{k}$. The total magnetic flux linked with the loop is:

              • 80 Wb
              • 16 Wb
              • \(8 \times 10^{-2}\) Wb
              • \(8 \times 10^{-3}\) Wb

            • 4.

              Consider a cylindrical conductor of length $l$ and area of cross-section $A$. Current $I$ is maintained in the conductor and electrons drift with velocity $\vec{v}_d$ ($|\vec{v}_d| = \frac{e|\vec{E}|}{m}\tau$), (where symbols have their usual meanings). Show that the conductivity $\sigma$ of the material of the conductor is given by

              $$\sigma = \frac{ne^2}{m}\tau.$$


                • 5.
                  The resistance of a metal wire at \(20^\circ\text{C}\) is \(1.05\,\Omega\) and at \(100^\circ\text{C}\) is \(1.38\,\Omega\). Determine the temperature coefficient of resistivity of this metal.


                    • 6.

                      (I) The real image of an object placed between $f$ and $2f$ from a convex lens can be seen on a screen placed at the image location. If the screen is removed, is the image still there? Explain.

                      (II) Plane and convex mirrors produce virtual images of objects. Can they produce real images under some circumstances? Explain.

                        CBSE CLASS XII Previous Year Papers

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