Question

Four alternatives are given for each of the following questions. Choose the correct
alternative and write the complete answer along with its letter of alphabet. 3x1
1. The device used to measure the current is
a) galvanometer b) ammeter c) voltmeter d) rheostat
2. Which of the following is not a characteristic of magnetic lines of force?
a) emerge from North pole
b) intersect each other
c) merge in South pole
d) do not intersect each other
3. Which type of lens you prefer to use in reading small words in newspape
a) concave lens with focal length 50 cm
b) convex lens with focal length 50 cm
c) concave lens with focal length 5cm
d) convex lens with focal length 5 cm
Answer the following questions:
4. Power of a lens is 2 diopter. What does it mean?
5. In which point of a lens the light ray do not bend?
Answer the following questions:
6. On what factors did the resistance of a conductor depends?
7. Draw a ray diagram of image formed when an object is placed bey
front of a concave lens
8. Compare the power used in in each of the following;
a) 6-volt battery in series with 1 ohm and 2-ohm resistors
b)4-volt battery in parallel with 12 ohm and 2-ohm resist
Answer the following questions:
9. Draw a neat diagram of electric motor and label carbon brushe
ulnin neyneriment to show convex lens converges light r
IV.​

Answer 1

Explanation:

1. The device used to measure the current is a) galvanometer.

2. Which of the following is not a characteristic of magnetic lines of force?

a) emerge from North pole

b) intersect each other

c) merge in South pole

d) do not intersect each other

3. Which type of lens you prefer to use in reading small words in newspaper* ( prevalent spelling error)

a) concave lens with focal length 50 cm

b) convex lens with focal length 50 cm

c) concave lens with focal length 5cm

d) convex lens with focal length 5 cm

4. Power of a lens is 2 diopter. This means that the focal length of the lens is 1/2 metres.

5. The light ray does not bend when it passes through optical center of the lens.

6. Resistance of conductor depends on the Resistivity, length of the conductor and the area if the conductor.

8. a)Voltage = 6V

Resistance = 1+2 = 3A

Power = V²/R = 12W

b) Resistance = (1/12 + 1/2)'s Reciprocal

= 12/7 Ohm

4²/(12/7)

= 9.33 W $.$

Answer 2

Question :

⠀⠀⠀⠀━━━ Four alternatives are given for each of the following questions. Choose the correct alternative :

⠀⠀1 ). The device used to measure the current is :

⠀⠀a). galvanometer ✔

⠀⠀b). ammeter

⠀⠀c). voltmeter

⠀⠀d). rheostat

⠀⠀⠀⠀⠀$\therefore {\underline{ \sf \:The\:Device\:used\:to\:measure \:the\:current is \bf Galvnometer \:\bf{[ \: Option\:A \:= \: Galvanometer \:] \:}}}$

⠀⠀⠀⠀⠀━━━━━━━━━━━━━━━━━━━⠀

⠀⠀2). Which of the following is not a characteristic of magnetic lines of force ?

⠀⠀a). emerge from north pole

⠀⠀b). intersect each other ✔

⠀⠀c). merge in South pole

⠀⠀d). do not intersect each other

⠀⠀⠀⠀⠀$\therefore {\underline{ \sf \:They\:\: \bf intersect \:each \:other \:\bf{[ \: Option\:B\:= \: Interest \:each\:other\:] \:}}}$

⠀⠀⠀⠀⠀━━━━━━━━━━━━━━━━━━━⠀

⠀⠀3). Which type of lens you prefer to use in reading small words in newspaper ?

⠀⠀a) concave lens with focal length 50 cm

⠀⠀b) convex lens with focal length 50 cm

⠀⠀c) concave lens with focal length 5cm

⠀⠀d) convex lens with focal length 5 cm ✔

⠀⠀⠀⠀⠀$\therefore {\underline{ \sf \:I \:prefer\: \bf convex \:lens \:with\:focal \:length\:5 \:cm \:\bf{[ \: Option\:D\:= convex \:lens \:with\:focal \:length\:5 \:cm\: \:] \:}}}$

⠀⠀⠀⠀⠀━━━━━━━━━━━━━━━━━━━⠀

⠀⠀━━━ Answer the following questions :

⠀⠀4 ). Power of a lens is 2 diopter. What does it mean ?

⠀⠀Ans : Power of a lens is 2 diopter means the focal length of lens is ½ cm .

⠀⠀⠀⠀⠀━━━━━━━━━━━━━━━━━━━⠀

⠀⠀5 ). In which point of a lens the light ray do not bend ?

⠀⠀Ans : The Light ray do not bend when it passes through optical center of lens .

⠀⠀⠀⠀⠀━━━━━━━━━━━━━━━━━━━⠀

⠀⠀6 ). On what factors did the resistance of a conductor depends ?

⠀⠀Ans : Resistance of conductor depends upon the resistivity , length of conductor and the cross sectional ⠀⠀⠀⠀area of the conductor .

⠀⠀⠀⠀⠀━━━━━━━━━━━━━━━━━━━⠀

⠀⠀⠀8.) Compare the power used in in each of the following;

⠀⠀⠀a) 6-volt battery in series with 1 ohm and 2-ohm resistors.

⠀⠀Ans :

⠀⠀⠀⠀⠀⠀As We know that ,

$\qquad \dag\:\:\bigg\lgroup \sf{Power \:: \bigg( \dfrac{V^2 }{R}\bigg) }\bigg\rgroup$

Here ,

• Battery Voltage [ V] : 6 V [ Volt ]
• Resistance [ R] : 1 ohm + 2 ohm = 3 $\Omega$

$\qquad:\implies \sf Power \:= \: \dfrac{6^2 }{3}$

$\qquad:\implies \sf Power \:= \: \dfrac{36 }{3}$

$\qquad:\implies \sf Power \:= \: 12 W$

Therefore,

⠀⠀⠀⠀⠀$\therefore {\underline{ \mathrm {\:Power\: \:is\:\bf{12\: W}}}}$

⠀⠀⠀⠀⠀━━━━━━━━━━━━━━━━━━━⠀

⠀⠀⠀b).4-volt battery in parallel with 12 ohm and 2-ohm resistors .

⠀⠀Ans :

⠀⠀⠀⠀⠀⠀ As We know that ,

$\qquad \dag\:\:\bigg\lgroup \sf{Power \:: \bigg( \dfrac{V^2 }{R} \bigg) }\bigg\rgroup$

Here ,

• Battery Voltage [ V] : 4 V [ Volt ]
• Parallel Resistance [ R] :

⠀⠀⠀For Prallel - Resistors :

$\qquad:\implies \sf \dfrac{1}{R_{eq}} = \dfrac{1}{R_1 } + \dfrac{1}{R_2 }$

$\qquad:\implies \sf \dfrac{1}{R_{eq}} = \dfrac{7}{12}$

$\qquad:\implies \sf R_{eq} = \dfrac{12}{7} \Omega$

⠀⠀⠀⠀⠀⠀$\underline {\boldsymbol{\star\:Now \: By \: Substituting \: the \: known \: Values \::}}$

$\qquad:\implies \sf Power \:= \: \dfrac{4^2 }{12/7}$

$\qquad:\implies \sf Power \:= \: 9.33 W$

Therefore,

⠀⠀⠀⠀⠀$\therefore {\underline{ \mathrm {\:Power\: \:is\:\bf{9.33\: W}}}}$

⠀⠀⠀⠀⠀━━━━━━━━━━━━━━━━━━━⠀

[ Note : Answer of Question 7 in Given attachment ( image ) . ]

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