Chapter 29

On measuring the diameter of a spherical body using vernier callipers, main scale reading \(=1.3 \mathrm{~cm}, 5\) th vernier scale division is coinciding with any main scale division and zero error is \(-0.03 \mathrm{~cm}\), what will be corrected reading? (a) \(1.38 \mathrm{~cm}\) (b) \(1.32 \mathrm{~cm}\) (c) \(1.35 \mathrm{~cm}\) (d) \(-1.38 \mathrm{~cm}\)

For measuring depth of a beaker using vernier callipers, observed readings are given as $$ \begin{array}{c|c|c} \hline \text { S.No. } & \text { MSR (cm) } & \text { VSD } \\ \hline \text { 1. } & 0.5 & 8 \\ \text { 2. } & 0.5 & 4 \\ \text { 3. } & 0.5 & 6 \\ \hline \end{array} $$ If zero error is \(-0.03 \mathrm{~cm}\), then mean corrected depth is (a) \(0.56 \mathrm{~cm}\) (b) \(0.59 \mathrm{~cm}\) (c) \(0.53 \mathrm{~cm}\) (d) \(0.52 \mathrm{~cm}\)

On measuring diameter of a wire with help of screw gauge, main scale reading is \(1 \mathrm{~mm}\) and 6 th division of circular scale lying over reference line. On measuring zero error, it is found that zero of circular scale has advanced from reference line by 3 divisions on circular scale, then corrected diameter is (a) \(1.09 \mathrm{~mm}\) (b) \(1.06 \mathrm{~mm}\) (c) \(1.03 \mathrm{~mm}\) (d) \(1.60 \mathrm{~mm}\)

Two screw gauges \(A\) and \(B\) have equal number of divisions on circular scale. \(A\) has pitch \(1 \mathrm{~mm}\) and \(B\) has pitch \(0.5 \mathrm{~mm}\). Which one is more accurate? (a) \(A\) (b) \(\underline{B}\) (c) Both (d) Can't say

Six rotations are given to a screw to turn it through a distance of \(3 \mathrm{~mm}\) and there are 50 divisions on the circular scale. What is the least count of the system? (a) \(0.01 \mathrm{~cm}\) (b) \(0.02 \mathrm{~mm}\) (c) \(0.001 \mathrm{~cm}\) (d) \(0.001 \mathrm{~mm}\)

If \(m\) and \(M\) are the masses of two bodies that are tied at two ends of a meter scale that is balanced on a sharp edge of a heavy broad wedge. If \(M=20 \mathrm{~g}\), its distance from centre \(=30 \mathrm{~cm}\) and distance of mass \(m\) from centre is \(25 \mathrm{~cm}\) when metre scale is balanced, then \(m\) is (a) \(23 \mathrm{~g}\) (b) \(24 \mathrm{~g}\) (c) \(25 \mathrm{~g}\) (d) \(26 \mathrm{~g}\)

If two masses \(M\) and \(m\) are tied to two ends of a meter scale. If a balanced point is obtained at point \(P\) and if \(M>m\), then (a) \(P A=P B\) (b) \(P A>P B\) (c) \(P B>P A\) (d) \(P A=3 P B\)

Two wires \(A\) and \(B\) have same lengths and made of the same material but \(A\) is thicker than \(B\). Both are subjected to the same extending load. Which will extend more? (a) \(A\) (b) \(B\) (c) Same extension (d) Can't predict

In experiment for measuring surface tension by capillary rise method, readings for positions \(A, B, C\) and \(D\) for internal diameter of capillary tube are given as under. Mean internal radius of capillary is \(\begin{aligned} &A(\mathrm{~cm})=1,000 \\ &B(\mathrm{~cm})=1,000 \\ &C(\mathrm{~cm})=1,000 \\ &D(\mathrm{~cm})=1,000 \end{aligned}\) (a) \(0.002 \mathrm{~cm}\) (b) \(0.003 \mathrm{~cm}\) (c) \(0.004 \mathrm{~cm}\) (d) \(0.005 \mathrm{~cm}\)

In an experiment for determining coefficient of viscosity, one lead shot \(A\) is having radius \(r_{1}\) and the other \(B\) is having \(\frac{r_{1}}{2}\). Which one will fall fast? (a) \(A\) (b) \(B\) (c) Both with same speed (d) Can't say

In the experiment of measuring speed of sound by resonance tube, it is observed that for tuning fork of frequency \(v=480 \mathrm{~Hz}\), length of air column \(\mathrm{cm}\), \(l_{1}=30 \mathrm{~cm}, l_{2}=70 \mathrm{~cm}\), then \(v_{1}\) is equal to (a) \(338 \mathrm{~ms}^{-1}\) (b) \(379 \mathrm{~ms}^{-1}\) (c) \(384 \mathrm{~ms}^{-1}\) (d) \(332 \mathrm{~ms}^{-1}\)

In an experiment to determine the specific heat of a given liquid by method of mixtures. If room temperature recorded by one thermometer is \(29^{\circ} \mathrm{C}\) and that by second thermometer is \(27.5^{\circ} \mathrm{C}\). If steady temperature of metal in hypsometer is \(62^{\circ} \mathrm{C}\). What will be corrected temperature of metal? (a) \(60^{\circ} \mathrm{C}\) (b) \(60.5^{\circ} \mathrm{C}\) (c) \(61^{\circ} \mathrm{C}\) (d) \(63.5^{\circ} \mathrm{C}\)

\(N\) divisions on the main scale of a vernier callipers coincide with \(N+1\) divisions of the vernier scale. If each division of main scale is \(a\) units, then least count of the instrument is (a) \(\frac{a}{N+1}\) (a) \(a\) (c) \(\frac{N}{N+1} \times a\) (d) \(\frac{a}{N}\)

Question Nos. 21 to 30 are Assertion-Reason type. Each of these contains two Statements: Statement 1 (Assertion), Statement Il (Reason). Each of these questions also has four alternative choice, only one of which is correct. You have to select the correct choices from the codes (a), (b), (c) and (d) given below (a) If both Assertion and Reason are true and the Reason is correct explanation of the Assertion (b) If both Assertion and Reason are true but Reason is not correct explanation of the Assertion (c) If Assertion is true but Reason is false (d) If Assertion is false but the Reason is true Assertion While operating Wheatstone bridge [PO box], in starting, the key of the battery is closed first and the key of the galvanometer is closed later and when the circuit is to be switched off then switches are released in the reverse order. Reason This is done to avoid the damage of galvanometer due to induced emf.

In comparison of emf's of two cells using potentiometer, the balanced length for batteries having emf \(E_{1}\) and \(E_{2}\) are \(60 \mathrm{~cm}\) and \(20 \mathrm{~cm}\), respectively. Then (a) \(\frac{E_{1}}{E_{2}}=3\) (b) \(\frac{E_{1}}{E_{2}}=\frac{1}{3}\) (c) \(\frac{E_{1}}{E_{2}}=60\) (d) \(\frac{E_{1}}{E_{2}}=20\)

In determination of refractive index of glass slab using travelling microscope, first of all we take a reading when the microscope is focused on a mark. This reading comes out to be \(s_{1}\), then we place a glass slab on the surface covering the mark. Now, the microscope is re-adjusted to focus the mark through the slab and this time reading comes out to be \(s_{2}\). Then, we place an opaque object on the glass slab and adjust the microscope to focus on opaque object, this time the reading of microscope is \(s_{3} .\) The refractive index of the glass slab is (a) \(\frac{s_{3}-s_{1}}{s_{2}-s_{1}}\) (b) \(\frac{s_{3}-s_{2}}{s_{2}-s_{1}}\) (c) \(\frac{s_{3}-s_{1}}{s_{3}-s_{2}}\) (d) \(\frac{s_{3}}{s_{3}-s_{2}}\)

The readings corresponding to zener diode are given below in the table. From given table, determine the reverse breakdown voltage of the zener diode. $$ \begin{array}{c|c|c|c|} \hline {\text { Forward bias }} & & {\text { Reverse bias }} \\ \hline V \text { (volt) } & I(\mathrm{~mA}) & V \text { (volt) } & I(\mu \mathrm{A}) \\ \hline 0.5 & 5 & 0.5 & 2.0 \\ 0.7 & 20 & 1.0 & 2.0 \\ 0.8 & 40 & 3.0 & 2.0 \\ 1.0 & 250 & 5.0 & 2.0 \\ & & 5.5 & 100.0 \\ & & 5.5 & 120.0 \\ \hline \end{array} $$ (a) It is lying between \(1.0 \mathrm{~V}\) to \(5.0 \mathrm{~V}\) (b) \(1.0 \mathrm{~V}\) (c) Approx. \(5.3 \mathrm{~V}\) (d) None of the above

When a glass capillary tube of radius \(0.015 \mathrm{~cm}\) is dipped in water, the water rises to a height of \(15 \mathrm{~cm}\) within it. Assuming contact angle between water and glass to be \(0^{\circ}\), the surface tension of water is \(\left[\rho_{\text {water }}=1000 \mathrm{~kg} \mathrm{~m}^{-3,} \mathrm{~g}=9.81 \mathrm{~ms}^{-2}\right]\) (a) \(0.11 \mathrm{Nm}^{-1}\) (b) \(0.7 \mathrm{Nm}^{-1}\) (c) \(0.072 \mathrm{Nm}^{-1}\) (d) None of the above

The zener diode normally operates under reverse bias condition, the major use of this fact is in the applications where we require (a) large value of current (b) a constant voltage (c) a current that is increasing without any change in applied voltage (d) All of the above

For CE configuration of a transistor, (a) input resistance is very small while output resistance is very high (b) input resistance is very large while output resistance is very small (c) both input and output resistances are very small (d) both input and output resistances are very large

Transfer characteristic for a transistor is plotted between (a) output current versus input current keeping output voltage constant (b) output current versus input current keeping input voltage constant (c) output current versus input voltage keeping output voltage constant (d) input current versus output voltage keeping input voltage constant

Consider the transistor shown in figure, its terminals are marked as 1,2 and 3 . Using multimeter one try to identify the base of transistor, he proceed in the way as follows Experiment I He touches the common lead of the multimeter to 2 , then on touching other lead of multimeter to 1 he hasn't got any beep (indication of conduction) but when connected to 3 got the beep. Experiment II He connects the common lead of multimeter to 1 and other lead to 2 and 3 one by one then in this case he got beep for both connections. From this we conclude that (a) 1 is base (b) 2 is base (c) 3 is base (d) None of these

In measurement of mass of a given object by the principle of moments, the meter scale is hung from its mid-point. A known weight of mass \(2 \mathrm{~kg}\) is hung at one end of meter scale and unknown weight of mass \(\mathrm{m} \mathrm{kg}\) is hung at \(20 \mathrm{~cm}\) from the centre on other side. The value of \(m\) is (a) \(2 \mathrm{~kg}\) (b) \(5 \mathrm{~kg}\) (c) \(2.5 \mathrm{~kg}\) (d) \(0.8 \mathrm{~kg}\)

While measuring surface tension of water using capillary rise method, height of the lower meniscus from free surface of water is \(3 \mathrm{~cm}\) while inner radius of capillary tube is found to be \(0.5 \mathrm{~cm}\). Then compute surface tension of water using this data. [Take contact angle between glass and water as \(0^{\circ}\) and \(\left.g=9.81 \mathrm{~ms}^{-2}\right]\) (a) \(0.72 \mathrm{Nm}^{-1}\) (b) \(0.77 \mathrm{Nm}^{-1}\) (c) \(1.67 \mathrm{Nm}^{-1}\) (d) None of the above

While measuring surface tension of water using capillary rise method the necessary precaution to be taken is/are (a) capillary tube should be clean while water should have some grease (b) both capillary tube and water should be clean (c) no need to take care of temperature of water (d) None of the above

A wide jar is filled with glycerine having specific gravity \(1.26\), in this jar, a steel ball of radius \(0.25 \mathrm{~cm}\) has been dropped. After some time it has been observed that ball is taking equal interval of time \((1.8 \mathrm{~s})\) to cover equal successive distances, of \(20 \mathrm{~cm} .\) [Take, \(\left.\rho_{\text {steel }}=7.8 \times 10^{3} \mathrm{~kg}-\mathrm{m}^{3}, g=9.81 \mathrm{~ms}^{-2}\right]\). The viscosity of glycerine is [in \(\mathrm{N}-\mathrm{sm}^{-2}\) ] (a) \(0.802\) (b) \(1.67\) (c) \(0.76\) (d) \(0.963\)

A spectrometer gives the following reading when used to measure the angle of a prism. Main scale reading : \(58.5\) degree Vernier scale reading : 09 divisions Given that 1 division on main scale corresponds to \(0.5\) degree. Total divisions on the vernier scale is 30 and match with 29 divisions of the main scale. The angle of the prism from the above data is (a) \(58.59^{\circ}\) (b) \(58.77^{\circ}\) (c) \(58.65^{\circ}\) (d) \(59^{\circ}\)

A screw gauge gives the following reading when used to measure the diameter of a wire. Main scale reading : \(0 \mathrm{~mm}\) Circular scale reading : 52 divisions Given that \(1 \mathrm{~mm}\) on main scale corresponds to 100 divisions of the circular scale. The diameter of wire from the above data is (a) \(0.052 \mathrm{~cm}\) (b) \(0.026 \mathrm{~cm}\) (c) \(0.005 \mathrm{~cm}\) (d) \(0.52 \mathrm{~cm}\)

An experiment is performed to find the refractive index of glass using a travelling microscope. In this experiment distances are measured by (a) vemier scale from microscope (b) a standard laboratory scale (c) a meter scale provided on the microscope (d) a screw gauge provided on the microscope

In an experiment the angles are required to be measured using an instrument. 29 divisions of the main scale exactly coincide with the 30 divisions of the vernier scale. If the smallest division of the main scale is half-a-degree (i.e., \(0.5^{\circ}\) ), then the least count of the instrument is (a) one minute (b) half minute (c) one degree (d) half degree

A A working transistor with its three legs marked \(P, Q\) and \(R\) is tested using a multimeter. No conduction is found between \(P\) and \(Q .\) By connecting the common (- ve) terminal of the multimeter to \(R\) and the other (positive) terminal to \(P\) or \(Q\), some conduction is seen on the multimeter. Which of the following is true for the transistor? (a) It is an \(n-p-n\) transistor with \(R\) as base (b) It is an \(p-n-p\) transistor with \(R\) as collection (c) It is a \(p-n-p\) transistor with \(R\) as emitter (d) It is an \(n-p-n\) transistor with \(R\) as collector