Advertisements
Advertisements
प्रश्न
The specification on a heater coil is 250 V, 500 W. Calculate the resistance of the coil. What will be the resistance of a coil of 1000 W to operate at the same voltage?
Advertisements
उत्तर
Let R be the resistance of the coil.
The power P consumed by a coil of resistance R when connected across a supply V is given by
\[P = \frac{V^2}{R}\]
\[ \Rightarrow R = \frac{V^2}{P}\]
\[ \Rightarrow R = \frac{\left( 250 \right)^2}{500} = 125 \Omega\]
Now, P = 1000 W
\[\Rightarrow R = \frac{V^2}{P} = \frac{\left( 250 \right)^2}{1000} = 62 . 5 \Omega\]
APPEARS IN
संबंधित प्रश्न
Show variation of resistivity of copper as a function of temperature in a graph.
Define the term 'conductivity' of a metallic wire. Write its SI unit.
Using the concept of free electrons in a conductor, derive the expression for the conductivity of a wire in terms of number density and relaxation time. Hence obtain the relation between current density and the applied electric field E.
Define the term 'electrical conductivity' of a metallic wire. Write its S.I. unit.
The following figure shows a conductor of length l with a circular cross-section. The radius of the cross-section varies linearly from a to b. The resistivity of the material is ρ. Assuming that b – a << l, find the resistance of the conductor.
The heat developed in a system is proportional to the current through it.
An electrolysis experiment is stopped and the battery terminals are reversed.
For a metallic conductor, what is the relation between current density (J), conductivity (σ) and electric field intensity (E)?
The ______, a property of materials C, Si, and Ge depends upon the energy gap between their conduction and valence bands.
Two cells of 1.25 V and 0.75 V are connected in series with anode of one connected to cathode of the other. The effective voltage will be ______.
Consider a current carrying wire (current I) in the shape of a circle.
Assertion: Bending a wire does not effect electrical resistance.
Reason: Resistance of wire is proportional to resistivity of material.
A man covers his body with a blanket of thickness 4 mm. His temperature is 37°C and that of the atmosphere is 27°C. If the coefficient of thermal conductivity of wool is 1.2 × 10-5 MKS units, heat lost by him per hour per square meter area is:
The resistivity of a wire ______
