A platinum resistance thermometer has a resistance of $50\,\Omega $ at $20\,^o C$. When dipped in a liquid the resistance becomes $76.8\,\Omega $. The temperature coefficient of resistance for platinum is $\alpha = 3.92 \times {10^{ - 3}}\,^o C$. The temperature of the liquid is .............. $^o C$
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A beam contains $2 \times 10^8$ doubly charged positive ions per cubic centimeter, all of which are moving with a speed of $10^5 \,m/s$. The current density is ............. $A/m^2$
Carbon resistor has resistance specified by three bands having colours red, yellow and black. If the resistor is remolded to make a resistor twice of previous length, the new colour code will be
If power dissipated in the $9 \,\Omega$ resistor in the circuit shown is $36\,W$, the potential difference across the $2 \,\Omega$ resistor is .......... $V$
An electric current flows along an insulated strip $PQ$ of a metallic conductor. The current density in the strip varies as shown in graph of figure. Which one of the following statements could explain this variation ?
Two heaters $A$ and $B$ have power rating of $1 \mathrm{~kW}$ and $2 \mathrm{~kW}$, respectively. Those two are first connected in series and then in parallel to a fixed power source. The ratio of power outputs for these two cases is:
Variation of current passing through a conductor as the voltage applied across its ends as varied is shown in the adjoining diagram. If the resistance $(R)$ is determined at the points $A$, $B$, $C$ and $D$, we will find that
The current in a conductor is expressed as $I=3 t^2+4 t^3$, where $I$ is in Ampere and $t$ is in second. The amount of electric charge that flows through a section of the conductor during $t=1$ s to $t=2 \mathrm{~s}$ is_______ C.
A student uses the resistance of a known resistor $(1 \,\Omega)$ to calibrate a voltmeter and an ammeter using the circuits shown below. The student measures the ratio of the voltage to current to be $1 \times 10^3 \,\Omega$ in circuit $(a)$ and $0.999 \,\Omega$ in circuit $(b)$. From these measurements, the resistance (in $\Omega$ ) of the voltmeter and ammeter are found to be close to
Figure shows a simple potentiometer circuit for measuring a small $e.m.f$. produced by a thermocouple. The meter wire $PQ$ has a resistance $5 \,\Omega$ and the driver cell has an e.m.f. of $2\, V$. If a balance point is obtained $0.600\, m$ along $PQ$ when measuring an e.m.f. of $6.00\, mV$, what is the value of resistance $R$ ............... $\Omega$