NEET Test Series from KOTA - 10 Papers In MS WORD
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PHXII03:CURRENT ELECTRICITY
357009
The mobility of free electrons (charge \(=e\), mass \(=m\) and relaxation time \(=\tau\) ) in a metal is proportional to
1 \(\frac{e}{m}\tau \)
2 \(\dfrac{m}{e} \tau\)
3 \(\dfrac{e}{m \tau}\)
4 \(\dfrac{m}{e \tau}\)
Explanation:
Drift velocity per unit electric field is called mobility of electrons. \(i.e.\,\,\,\,\,\,\,\mu = \frac{{{v_d}}}{E} = \frac{{eE}}{{Em}}\tau \) \(\therefore \,\,\,\,\,\,\,\,\,\mu = \frac{{e\tau }}{m}\)
PHXII03:CURRENT ELECTRICITY
357010
Assertion : The electric bulbs glow immediately when switch is on. Reason : The drift velocity of electrons in a metallic wire is very high
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
When we close the circuit by turning on the switch, an electric field is established instantlywhich causes electrons to drift at every portion of the circuit. Electric current is set up immediately and does not wait for the electrons to flow from one end of the conductor to the other end. So correct option is (3).
PHXII03:CURRENT ELECTRICITY
357011
In the absence of applied potential, the electric current flowing through a metallic wire is zero because
1 The electron move in random direction with speed of the order close to that of velocity of light
2 The electrons are drifted in random direction with a speed of the order of \({10^{ - 2}}cm/s\)
3 Electrons and ions move in opposite direction
4 The electrons remain stationary
Explanation:
The drift velocity is small and random. It is of the order of \({10^{ - 2}}cm/s\). When the potential is applied, the electric field is setup with the speed of light. When no potential is applied, the random motion does not contribute to the motion of the charge in a specific direction.
PHXII03:CURRENT ELECTRICITY
357012
Charge passing through a conductor of cross-section area \(A = 0.3\;{m^2}\) is given by \(q=3 t^{2}+5 t+2\) in coulomb, where \(t\) is in second. What is the value of drift velocity at \(t=2 s\) ? (Given, \(n = 2 \times {10^{25}}{\rm{/}}{m^2}\))
1 \(0.77 \times {10^{ - 5}}\;m{\rm{/}}s\)
2 \(1.77 \times {10^{ - 5}}\;m{\rm{/}}s\)
3 \(2.08 \times {10^5}\;m{\rm{/}}s\)
4 \(0.57 \times {10^{ - 5}}\;m{\rm{/}}s\)
Explanation:
Cross - sectional area of conductor, \(A = 0.3\;{m^2}\) and \(n = 2 \times {10^{25}}\;{m^{ - 2}}\) Charge, \(q=3 t^{2}+5 t+2 C\) Current, \(i=\dfrac{d q}{d t}=6 t+5=17 A[\because t=2]\) We also have \(i=n e A v_{d}\) Drift velocity, \(v_{d}=\dfrac{i}{n e A}\) \(=\dfrac{17}{2 \times 10^{25} \times 1.6 \times 10^{-19} \times 0.3}\) \( = \frac{{17}}{{0.96 \times {{10}^6}}} = 1.77 \times {10^{ - 5}}\;m{\rm{/}}s\) So, correct option is (2).
357009
The mobility of free electrons (charge \(=e\), mass \(=m\) and relaxation time \(=\tau\) ) in a metal is proportional to
1 \(\frac{e}{m}\tau \)
2 \(\dfrac{m}{e} \tau\)
3 \(\dfrac{e}{m \tau}\)
4 \(\dfrac{m}{e \tau}\)
Explanation:
Drift velocity per unit electric field is called mobility of electrons. \(i.e.\,\,\,\,\,\,\,\mu = \frac{{{v_d}}}{E} = \frac{{eE}}{{Em}}\tau \) \(\therefore \,\,\,\,\,\,\,\,\,\mu = \frac{{e\tau }}{m}\)
PHXII03:CURRENT ELECTRICITY
357010
Assertion : The electric bulbs glow immediately when switch is on. Reason : The drift velocity of electrons in a metallic wire is very high
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
When we close the circuit by turning on the switch, an electric field is established instantlywhich causes electrons to drift at every portion of the circuit. Electric current is set up immediately and does not wait for the electrons to flow from one end of the conductor to the other end. So correct option is (3).
PHXII03:CURRENT ELECTRICITY
357011
In the absence of applied potential, the electric current flowing through a metallic wire is zero because
1 The electron move in random direction with speed of the order close to that of velocity of light
2 The electrons are drifted in random direction with a speed of the order of \({10^{ - 2}}cm/s\)
3 Electrons and ions move in opposite direction
4 The electrons remain stationary
Explanation:
The drift velocity is small and random. It is of the order of \({10^{ - 2}}cm/s\). When the potential is applied, the electric field is setup with the speed of light. When no potential is applied, the random motion does not contribute to the motion of the charge in a specific direction.
PHXII03:CURRENT ELECTRICITY
357012
Charge passing through a conductor of cross-section area \(A = 0.3\;{m^2}\) is given by \(q=3 t^{2}+5 t+2\) in coulomb, where \(t\) is in second. What is the value of drift velocity at \(t=2 s\) ? (Given, \(n = 2 \times {10^{25}}{\rm{/}}{m^2}\))
1 \(0.77 \times {10^{ - 5}}\;m{\rm{/}}s\)
2 \(1.77 \times {10^{ - 5}}\;m{\rm{/}}s\)
3 \(2.08 \times {10^5}\;m{\rm{/}}s\)
4 \(0.57 \times {10^{ - 5}}\;m{\rm{/}}s\)
Explanation:
Cross - sectional area of conductor, \(A = 0.3\;{m^2}\) and \(n = 2 \times {10^{25}}\;{m^{ - 2}}\) Charge, \(q=3 t^{2}+5 t+2 C\) Current, \(i=\dfrac{d q}{d t}=6 t+5=17 A[\because t=2]\) We also have \(i=n e A v_{d}\) Drift velocity, \(v_{d}=\dfrac{i}{n e A}\) \(=\dfrac{17}{2 \times 10^{25} \times 1.6 \times 10^{-19} \times 0.3}\) \( = \frac{{17}}{{0.96 \times {{10}^6}}} = 1.77 \times {10^{ - 5}}\;m{\rm{/}}s\) So, correct option is (2).
357009
The mobility of free electrons (charge \(=e\), mass \(=m\) and relaxation time \(=\tau\) ) in a metal is proportional to
1 \(\frac{e}{m}\tau \)
2 \(\dfrac{m}{e} \tau\)
3 \(\dfrac{e}{m \tau}\)
4 \(\dfrac{m}{e \tau}\)
Explanation:
Drift velocity per unit electric field is called mobility of electrons. \(i.e.\,\,\,\,\,\,\,\mu = \frac{{{v_d}}}{E} = \frac{{eE}}{{Em}}\tau \) \(\therefore \,\,\,\,\,\,\,\,\,\mu = \frac{{e\tau }}{m}\)
PHXII03:CURRENT ELECTRICITY
357010
Assertion : The electric bulbs glow immediately when switch is on. Reason : The drift velocity of electrons in a metallic wire is very high
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
When we close the circuit by turning on the switch, an electric field is established instantlywhich causes electrons to drift at every portion of the circuit. Electric current is set up immediately and does not wait for the electrons to flow from one end of the conductor to the other end. So correct option is (3).
PHXII03:CURRENT ELECTRICITY
357011
In the absence of applied potential, the electric current flowing through a metallic wire is zero because
1 The electron move in random direction with speed of the order close to that of velocity of light
2 The electrons are drifted in random direction with a speed of the order of \({10^{ - 2}}cm/s\)
3 Electrons and ions move in opposite direction
4 The electrons remain stationary
Explanation:
The drift velocity is small and random. It is of the order of \({10^{ - 2}}cm/s\). When the potential is applied, the electric field is setup with the speed of light. When no potential is applied, the random motion does not contribute to the motion of the charge in a specific direction.
PHXII03:CURRENT ELECTRICITY
357012
Charge passing through a conductor of cross-section area \(A = 0.3\;{m^2}\) is given by \(q=3 t^{2}+5 t+2\) in coulomb, where \(t\) is in second. What is the value of drift velocity at \(t=2 s\) ? (Given, \(n = 2 \times {10^{25}}{\rm{/}}{m^2}\))
1 \(0.77 \times {10^{ - 5}}\;m{\rm{/}}s\)
2 \(1.77 \times {10^{ - 5}}\;m{\rm{/}}s\)
3 \(2.08 \times {10^5}\;m{\rm{/}}s\)
4 \(0.57 \times {10^{ - 5}}\;m{\rm{/}}s\)
Explanation:
Cross - sectional area of conductor, \(A = 0.3\;{m^2}\) and \(n = 2 \times {10^{25}}\;{m^{ - 2}}\) Charge, \(q=3 t^{2}+5 t+2 C\) Current, \(i=\dfrac{d q}{d t}=6 t+5=17 A[\because t=2]\) We also have \(i=n e A v_{d}\) Drift velocity, \(v_{d}=\dfrac{i}{n e A}\) \(=\dfrac{17}{2 \times 10^{25} \times 1.6 \times 10^{-19} \times 0.3}\) \( = \frac{{17}}{{0.96 \times {{10}^6}}} = 1.77 \times {10^{ - 5}}\;m{\rm{/}}s\) So, correct option is (2).
357009
The mobility of free electrons (charge \(=e\), mass \(=m\) and relaxation time \(=\tau\) ) in a metal is proportional to
1 \(\frac{e}{m}\tau \)
2 \(\dfrac{m}{e} \tau\)
3 \(\dfrac{e}{m \tau}\)
4 \(\dfrac{m}{e \tau}\)
Explanation:
Drift velocity per unit electric field is called mobility of electrons. \(i.e.\,\,\,\,\,\,\,\mu = \frac{{{v_d}}}{E} = \frac{{eE}}{{Em}}\tau \) \(\therefore \,\,\,\,\,\,\,\,\,\mu = \frac{{e\tau }}{m}\)
PHXII03:CURRENT ELECTRICITY
357010
Assertion : The electric bulbs glow immediately when switch is on. Reason : The drift velocity of electrons in a metallic wire is very high
1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.
2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.
3 Assertion is correct but Reason is incorrect.
4 Assertion is incorrect but reason is correct.
Explanation:
When we close the circuit by turning on the switch, an electric field is established instantlywhich causes electrons to drift at every portion of the circuit. Electric current is set up immediately and does not wait for the electrons to flow from one end of the conductor to the other end. So correct option is (3).
PHXII03:CURRENT ELECTRICITY
357011
In the absence of applied potential, the electric current flowing through a metallic wire is zero because
1 The electron move in random direction with speed of the order close to that of velocity of light
2 The electrons are drifted in random direction with a speed of the order of \({10^{ - 2}}cm/s\)
3 Electrons and ions move in opposite direction
4 The electrons remain stationary
Explanation:
The drift velocity is small and random. It is of the order of \({10^{ - 2}}cm/s\). When the potential is applied, the electric field is setup with the speed of light. When no potential is applied, the random motion does not contribute to the motion of the charge in a specific direction.
PHXII03:CURRENT ELECTRICITY
357012
Charge passing through a conductor of cross-section area \(A = 0.3\;{m^2}\) is given by \(q=3 t^{2}+5 t+2\) in coulomb, where \(t\) is in second. What is the value of drift velocity at \(t=2 s\) ? (Given, \(n = 2 \times {10^{25}}{\rm{/}}{m^2}\))
1 \(0.77 \times {10^{ - 5}}\;m{\rm{/}}s\)
2 \(1.77 \times {10^{ - 5}}\;m{\rm{/}}s\)
3 \(2.08 \times {10^5}\;m{\rm{/}}s\)
4 \(0.57 \times {10^{ - 5}}\;m{\rm{/}}s\)
Explanation:
Cross - sectional area of conductor, \(A = 0.3\;{m^2}\) and \(n = 2 \times {10^{25}}\;{m^{ - 2}}\) Charge, \(q=3 t^{2}+5 t+2 C\) Current, \(i=\dfrac{d q}{d t}=6 t+5=17 A[\because t=2]\) We also have \(i=n e A v_{d}\) Drift velocity, \(v_{d}=\dfrac{i}{n e A}\) \(=\dfrac{17}{2 \times 10^{25} \times 1.6 \times 10^{-19} \times 0.3}\) \( = \frac{{17}}{{0.96 \times {{10}^6}}} = 1.77 \times {10^{ - 5}}\;m{\rm{/}}s\) So, correct option is (2).
