Questions
Filament of torch bulb is ?
- A metal case
- Metal tip at the centre of the base
- 2 thick wires
- Thin wires
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:
- $\frac { 4 U } { P }$
- $\frac { U } { P }$
- $\frac { 2 U } { P }$
- $\frac { 2 P } { 6U }$
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:
- open electric circuit
- closed electric circuit
- complete electric circuit
- both b and c
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
- $\dfrac { 8\varepsilon }{ 5 } $
- zero
- $\dfrac { 4\varepsilon }{ 5 } $
- $\dfrac { 2\varepsilon }{ 5 } $
State whether given statement is True or False
We use battery cell in our everyday life ?
- True
- False
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
- $4$
- $6$
- $8$
- $9$
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.
- 3V
- 4V
- 1.5V
- 2.5V
How many cells each marked ( 12V - A) should be connected in mixed grouping so that it may be marked as ( 48 V- 18 A)
- 4
- 8
- 12
- 16
Why the bulb brighter in a simple circuit that has more cells?
- Because the flow of electricity is more
- Because the flow of electricity is same
- Because the flow of electricity is less
- None of these
Two Leclanche cells assisting each other could be balanced on a length $L$ of a potentiometer wire. If the current through the wire is halved, what will be balancing length for one Leclanche cell?
- $L/4$
- $L/2$
- $L$
- $2L$
The two ends of a copper conductor of length 3.2 cm are connected to a battery acceleration of free electrons is
- $ 2 \times 10^{14} ms^{-2} $
- $ 3 \times 10^{14} ms^{-2} $
- $ 4 \times 10^{14} ms^{-2} $
- $ 5 \times 10^{14} ms^{-2} $
A cell in which chemical energy is converted into electric energy by first passing a current through it is called a _________.
- Primary cell
- Secondary cell
- Photocell
- Electrostatic machine
What is the $-$ve terminal of dry cell made up of?
- Carbon rod
- Zinc plate
- Magnesium plate
- Cadmium rod
In secondary cells:
- Chemical changes can be reversed by heating electrodes
- Chemical changes can be reversed by passing electric current
- Current is produced by photo chemical reactions
- None of these
Three types of electric cells which provide current are:
- Button cell, solar cell & secondary cell
- Solar cell, electrolytic cell, electro chemical cell
- $(A)$ and $(B)$ both are correct
- Neither $(A)$ nor $(B)$ is correct
What is the direction of flow of current inside a dry cell?
- from $+$ve to $-$ve terminal
- from $-$ve to $+$ve terminal
- from $+$ve to $+$ve terminal
- from $-$ve to $-$ve terminal
The cartridge in a dry cell contains :
- manganese dioxide and ammonium chloride
- manganese dioxide and zinc dust
- ammonium chloride and zinc dust
- manganese dioxide and activated carbon
- True
- False
The longer lead of a LED is always connected to the negative terminal of the battery and the shorter lead is connected to the posltlve terminal of the battery
- True
- False
- Ambiguous
- Data insufficient