Tag: electric cell

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Questions Related to electric cell

Multiple choice physics chemical effects of electric current study about cells electric cell types of cells

Filament of torch bulb is ?

  1. A metal case

  2. Metal tip at the centre of the base

  3. 2 thick wires

  4. Thin wires
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A filament of a bulb is spirally wounded wire inside the bulb supported by two thick wires at its ends. The filament is wire, which is mostly made up of tungsten. 

As electric current passes through the filament, it glows to produce light.

Multiple choice physics chemical effects of electric current study about cells electric cell types of cells

An inductor coil stores $U$ when a current is passed through it and dissipates heat energy at the rate of $P .$ The time constant of the circuit when this connected across a battery of zero internal resistance is:


  1. $\frac { 4 U } { P }$
  2. $\frac { U } { P }$
  3. $\frac { 2 U } { P }$
  4. $\frac { 2 P } { 6U }$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Energy stored U = (1/2)LI^2. Power dissipated P = I^2R. Time constant tau = L/R. From equations, L = 2U/I^2 and R = P/I^2. Thus, tau = (2U/I^2) / (P/I^2) = 2U/P.

Multiple choice physics chemical effects of electric current study about cells electric cell types of cells

An electric circuit which starts from one terminal of a cell and ends at the other terminal of the cell without any break is called:

  1. open electric circuit

  2. closed electric circuit

  3. complete electric circuit

  4. both b and c
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A circuit that provides a continuous path for current from one terminal to the other is called a closed or complete circuit.

Multiple choice physics chemical effects of electric current study about cells electric cell types of cells

Five cells each of emf $\varepsilon $ and internal resistance r each are connected in series. If one cell is connected wrongly, then potential difference across this cell will be

  1. $\dfrac { 8\varepsilon }{ 5 } $

  2. zero
  3. $\dfrac { 4\varepsilon }{ 5 } $
  4. $\dfrac { 2\varepsilon }{ 5 } $
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When five cells of emf epsilon and internal resistance r are in series, the total emf is 5 epsilon and total internal resistance is 5r. If one cell is connected with reverse polarity, the net emf becomes 5 epsilon - 2 epsilon = 3 epsilon, and the current in the circuit is I = (3 epsilon) / (5r). The potential difference across the wrongly connected cell is V = epsilon_cell + I*r = epsilon + ((3 epsilon)/(5r))*r = epsilon + (3/5)epsilon = (8 epsilon) / 5.

Multiple choice physics chemical effects of electric current study about cells electric cell types of cells

A wire of length $L$ and $3$ identical cells of negligible internal resistances are connected in series. Due to the current, the temperature of the wire is raised by $\Delta\ T$ in a time $t$. A number $N$ of similar cells is now connected in series with a wire of the same material and cross-section but of length $2\ L$. The temperature of the wire is raised by the same amount $\Delta\ T$ in the same time. The value of $N$ is

  1. $4$
  2. $6$
  3. $8$
  4. $9$
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice physics chemical effects of electric current study about cells electric cell types of cells

Two cells of emf's $3V$ and $3V$ have internal resistances  $1.5\Omega\ &\ 1\Omega$ are connected in parallel across $3\Omega,$ such that they send the current through $3\Omega$ in same direction calculate the p.d. across $3\Omega$ resistor.

  1. 3V

  2. 4V

  3. 1.5V

  4. 2.5V
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Two cells of emf 3V with internal resistances 1.5 ohm and 1 ohm are connected in parallel, so their equivalent emf E_eq = (E1/r1 + E2/r2) / (1/r1 + 1/r2) = (3/1.5 + 3/1) / (1/1.5 + 1/1) = (2 + 3) / (2/3 + 1) = 5 / (5/3) = 3V. The equivalent internal resistance r_eq = (1.5 * 1) / (1.5 + 1) = 1.5 / 2.5 = 0.6 ohm. When connected across a 3 ohm resistor, the potential difference is V = E_eq * R / (R + r_eq) = 3 * 3 / (3 + 0.6) = 9 / 3.6 = 2.5V.

Multiple choice physics chemical effects of electric current study about cells electric cell types of cells

Why the bulb brighter in a simple circuit that has more cells?

  1. Because the flow of electricity is more

  2. Because the flow of electricity is same

  3. Because the flow of electricity is less

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Adding more cells in series increases the total voltage of the circuit, which increases the current flowing through the bulb, making it brighter.