Explain how do we classify materials as conductor and insulators on the basis of their resistance.
Explain how do we classify materials as conductor and insulators on the basis of their resistance.
Conductors are the materials, which have a large number of free electrons $\left(\simeq10^{28} m ^{-3}\right)$ and small resistivity $\left(\simeq10^{-8} \Omega m \right)$. The resistivity of an ideal conductor is zero and it increases with the rise in temperature in metals.
Insulators are the substances, which have no practically free electrons and have very high resistivity $\left(\simeq 10^{16} \Omega m \right)$. The resistivity of an ideal insulator is infinity and decreases with the rise in temperature. Mica, rubber, glass porcelain are some examples of insulator.
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$(i)$ Name and state the law that gives relationship between the current through a conductor and the potential difference across its two terminals. Also, express this law mathematically.
$(ii)$ Draw the $V-I$ graph for this law. Justify your answer.
$(iii)$ Write the name and use of the circuit components whose symbols are given below.
$(i)$ Name and state the law that gives relationship between the current through a conductor and the potential difference across its two terminals. Also, express this law mathematically.
$(ii)$ Draw the $V-I$ graph for this law. Justify your answer.
$(iii)$ Write the name and use of the circuit components whose symbols are given below.
$(a)$ What do the following symbols represent in a circuit ? Write the name and one function of each.
$(b)$ Draw a schematic diagram of a circuit consisting of a battery of $12 V$, three resistors of $5\, \Omega, 10\, \Omega$ and $20\, \Omega$ connected in parallel, an ammeter to measure the total current through the circuit, $a$ voltmeter to measure the potential difference across the combination of resistors.
$(c)$ State any one advantage of connecting electrical devices in parallel with the mains instead of connecting them in series in a household circuit.
$(a)$ What do the following symbols represent in a circuit ? Write the name and one function of each.
$(b)$ Draw a schematic diagram of a circuit consisting of a battery of $12 V$, three resistors of $5\, \Omega, 10\, \Omega$ and $20\, \Omega$ connected in parallel, an ammeter to measure the total current through the circuit, $a$ voltmeter to measure the potential difference across the combination of resistors.
$(c)$ State any one advantage of connecting electrical devices in parallel with the mains instead of connecting them in series in a household circuit.
Nichrome is used to make the element of electric heater. Why ?
Nichrome is used to make the element of electric heater. Why ?