Use the data in the table given below and answer the following questions.
| Material | Resistivity | |
| Conductors | Silver | 1.60 × 10–8 |
| Copper | 1.62 × 10–8 | |
| Aluminum | 2.63 × 10–8 | |
| Tungsten | 5.20 × 10–8 | |
| Nickel | 6.84 × 10–8 | |
| Iron | 10.0 × 10–8 | |
| Chromium | 12.9 × 10–8 | |
| Mercury | 94.0 × 10 –8 | |
| Manganese | 1.84 × 10–6 | |
| Alloys | Constantan | 49 × 10–6 |
| Manganin | 44 × 10–6 | |
| Nichrome | 100 × 10–6 | |
| Insulators | Glass | 1010 – 1014 |
| Hard rubber | 1013 – 1016 | |
| Ebonite | 1015 – 1017 | |
| Diamond | 1012 - 1013 | |
| Paper (dry) | 1012 |
a. Which iron and mercury is a better conductor?
b. Which material is the best conductor?
a. Iron is a better conductor than mercury because the resistivity of mercury is more than the resistivity of iron.
b. Among all the materials listed in the table, silver is the best conductor because the resistivity of silver is lowest among all, i.e., 1.60 × 10–8
Answered by Vishal kumar | 2 years agoExplain the following.
a. Why is the tungsten used almost exclusively for filament of electric lamps?
b. Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?
c. Why is the series arrangement not used for domestic circuits?
d. How does the resistance of a wire vary with its area of cross-section?
e. Why copper and aluminum wires are usually employed for electricity transmission?
An electric heater of resistance 8 Ω draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.
Which uses more energy, a 250 W TV set in 1 hr, or a 1200 W toaster in 10 minutes?
Two lamps, one rated 100 W at 220 V, and the other 60 W at 220 V, are connected in parallel to the electric mains supply. What current is drawn from the line if the supply voltage is 220 V?
Compare the power used in the 2 Ω resistor in each of the following circuits:
(i) a 6 V battery in series with 1 Ω and 2 Ω resistors, and
(ii) a 4 V battery in parallel with 12 Ω and 2 Ω resistors.