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Set 5 of 25 · Questions 121-150 of 723

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JEE Main Physics · Current Electricity · Set 5 (Q121-150)

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  1. 121.
    A potentiometer is an accurate and versatile device to make electrical measurements of E.M.F. because the method involves:
    1. (1)cells
    2. (2)potential gradients
    3. (3)a condition of no current flow through the galvanometer
    4. (4)a combination of cells, galvanometer and resistance
  2. 122.
    An electric power line having total resistance of , delivers 1 kW of power at 250 V. The percentage efficiency of transmission line is .
    1. (1)100
    2. (2)92.5
    3. (3)96.9
    4. (4)86.5
  3. 123.
    Across a metallic conductor of non-uniform cross section a constant potential difference is applied. The quantity which remains constant along the conductor is
    1. (1)current
    2. (2)drift velocity
    3. (3)electric field
    4. (4)current density
  4. 124.
    In potentiometer experiment, the balancinglength is when two cells and are joined in series. When two cells are connected in opposition the balancing length is . The ratio of the e.m.f. of the two cells is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  5. 125.
    Identify the correct statement among the following:
    1. (1)Resistivity of metals decreases with temperature because more electrons are available for conduction.
    2. (2)Resistivity of metals increases with temperature because number of electrons decreases.
    3. (3)Resistivity of metals increases with temperature because number of collisions between electrons increases
    4. (4)Resistivity of metals decreases with temperature because superconductivity sets in.
  6. 126.
    Given below are two statements: one is labelled as Assertion and the other is labelled as Reason .
    Assertion An electron microscope can achieve better resolving power than an optical microscope.
    Reason The de Broglie's wavelength of the electrons emitted from an electron gun is much less than wavelength of visible light.
    choose the correct answer from the options given below:
    1. (1) is true but is false.
    2. (2)Both and are true but is NOT the correct explanation of .
    3. (3)Both and are true and is the correct explanation of .
    4. (4) is false but is true.
  7. 127.
    A galvanometer has resistance of and a current of produces full scale deflection in it. The resistance to be connected to it in series, to get a voltmeter of range 50 volt is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  8. 128.
    A metal has conduction electrons per and its resistivity is . m. If the drift speed of an electron in the metal is then its mean free path is (mass of electron and charge of electron
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  9. 129.
    A potentiometer consists of a wire of length 4 and resistance 10 . It is connected to a cell of e.m.f. ne potential difference per unit length of the wire will be
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  10. 130.
    A circuit to verify Ohm's law uses ammeter and voltmeter in series or parallel connected correctly to the resistor. In the circuit
    1. (1)Ammeter is always connected in series and voltmeter in parallel
    2. (2)Both ammeter and voltmeter must be connected in parallel
    3. (3)Ammeter is always used in parallel and voltmeter is series
    4. (4)Both ammeter and voltmeter must be connected in series
  11. 131.
    The H amount of thermal energy is developed by a resistor in 10 s when a current of 4A is passed through it. If the current is increased to 16A, the thermal energy developed by the resistor in 10 s will be:
    1. (1)H
    2. (2)16H
    3. (3)
    4. (4)4H
  12. 132.
    A potentiometer balances at when a cell of internal resistance is in the secondary circuit. To obtain the balancing point at , the resistance to be connected parallel to cell is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  13. 133.
    A resistor develops of thermal energy in when a current of is passed through it. If the currentis increased from to , what will be the energy developed in
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  14. 134.
    A carbon resistor of is to be marked with rings of different colours for its identification. The colour code sequence will be
    1. (1)Violet‐Yellow‐Orange‐Silver
    2. (2)Yellow‐Violet‐Orange‐Silver
    3. (3)Yellow‐Green‐Violet‐Gold
    4. (4)Green‐Orange‐Violet‐Gold
  15. 135.
    The masses of the wires of copper is in the ratio of 1 : 3 : 5 and their lengths are in the ratio of 5: 3: 1. The ratio of their electrical resistance is
    1. (1)1 : 3 : 5
    2. (2)5 : 3 : 1
    3. (3)1: 25: 125
    4. (4)125: 15: 1
  16. 136.
    The resistance of a wire is R ohm. If it is melted and stretched to n times its original length, its new resistance will be [NEET 2017]
    1. (1)nr
    2. (2)
    3. (3)
    4. (4)
  17. 137.
    The resistance of the bulb filament is at a temperature of . If its temperature coefficient of resistance be 0.005 per , its resistance will become at a temperature
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  18. 138.
    In the potentiometer, when the cell in the secondary circuit is shunted with resistance, the balance is obtained at the length 120 cm of wire. Now when the same cell is shunted with resistance, the balance is shifted to a length of 180 cm. The internal resistance of cell is
    1. (1)4
    2. (2)12
    3. (3)6
    4. (4)3
  19. 139.
    Assertion (A): When a wire of aluminium and another wire of silicon are heated from room temperature to , then conductivity of aluminium increases and that of silicon decreases.
    Reason (R): Aluminium has positive temperature coefficient of resistivity and silicon has negative temperature coefficient of resistivity.
    1. (1)Both (A) and (R) are correct and (R) is the correct explanation of .
    2. (2)Both (A) and (R) are correct but (R) is not the correct explanation of .
    3. (3)(A) is correct but ( ) is not correct.
    4. (4)
  20. 140.
    A galvanometer having a coil resistance gives a full-scale deflection when a current of is passed through it. What is the value of the resistance which can convert this galvanometer into a voltmeter giving full scale deflection for a potential difference of ?
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  21. 141.
    A tungsten light bulb has a resistance of when it as turned ON and when turned OFF. The ambient room temperature is . Find the temperature of the filament when the bulb is turned ON. (Let )
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  22. 142.
    A current through a wire depends on time as where A/s and . Find the charge crossed through a section of the wire in 15 s.
    1. (1)2100C
    2. (2)260C
    3. (3)2250C
    4. (4)11250C
  23. 143.
    Consider four conducting materials copper, tungsten, mercury and aluminium with resistivity and respectively
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  24. 144.
    The four bands of a colour coded resistor are of the colours grey, red, gold and gold. The value of the resistance of the resistor is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  25. 145.
    10 resistors, each of resistance R are connected in series to a battery of emf E and negligible internal resistance. Then, those are connected in parallel to the same battery, the current is increased n times. The value of n is [NEET 2023]
    1. (1)100
    2. (2)1
    3. (3)1000
    4. (4)10
  26. 146.
    Two wires of the same metal have same length, but their cross‐sections are in the ratio 3: 1. They are joined in series. The resistance of thicker wire is 10 . The total resistance of the combination will be
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  27. 147.
    Two coils require 20 minutes and 60 minutes respectively to produce same amount of heat energy when connected separately to the same source. If they are connected in parallel arrangement to the same source; the time required to produce same amount of heat by the combination of coils, will be__________min.
  28. 148.
    Two wires and are made up of the same material and have the same mass. Wire has radius of and wire has radius of . The resistance of wire is . The resistance of wire is ______ .
  29. 149.
    When two resistance and connected in series and introduced into the left gap of a meter bridge and a resistance of 10 Ω is introduced into the right gap, a null point is found at 60 cm from left side. When and are connected in parallel and introduced into the left gap, a resistance of 3Ω is introduced into the right-gap to get null point at 40 cm from left end. The product of is_____
  30. 150.
    The current in a conductor is expressed as , where is in Ampere and is in second. The amount of electric charge that flows through a section of the conductor during to is ____C.