Question

1. A concave mirror forms a real and enlarged image of an object if the object is placed at/between
(a) 2F (b) F (c)F and C (d)F and P
2. When a ray goes from an optically rarer medium to a denser medium, it
(a) goes straight (b)bends away from normal
(c) bends towards normal (d) reflect back
3. A current of 1 A is drawn by a filament of an electric bulb. Number of electrons passing through a cross section of the filament in 16 seconds would be roughly
(a) 1020 (b) 1016 (c) 1018 (d) 1023
4. A student carries out an experiment and plots the V-I graph of three samples of nichrome wire with resistances R1, R2 and R3 respectively (Figure 5). Which of the following is true?
(a) R1 = R2 = R3
(b) R1 >R2 >R3
(c) R3 >R2 >R1
(d) R2 >R3 >R1v

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Answer 1

Answer:

1.

F AND C

2.

A

I AM SURE

PLS MARK ME AS BRAINLIST

Answer 2

Question:- 1. A concave mirror forms a real and enlarged image of an object if the object is placed at/between

(a) 2F (b) F (c)F and C (d)F and P⤵

Answer 1:-⤵

Option (b) is the correct answer of your question.

For concave mirrors, when the object is between C and F, the image will be beyond C and will be enlarged and inverted.

Question 2:- When a ray goes from an optically rarer medium to a denser medium, it

(a) goes straight (b)bends away from normal

(c) bends towards normal (d) reflect back⤵

Answer 2:-⤵

Refraction is the bending of light rays after entering a medium where its speed is different. Due to refraction of light, when a ray of light passes from a rarer medium to a denser medium, bends towards the normal to the boundary between the two media.

Question 3:- A current of 1 A is drawn by a filament of an electric bulb. Number of electrons passing through a cross section of the filament in 16 seconds would be roughly⤵

Answer 3:-⤵

The relationship between current, charge and time is given as follows.

charge = current x time, that is, Q = It where,

charge is Q, it is measured in coulombs (C)

current is I, it is measured in amperes (A)

time is t, it is measured in seconds (s).

The relationship between electronic charge, charge and number of electrons are protons is given as follows.

charge = number of electrons or protons x electronic charge, that is Q = ne

where,

charge is Q, it is measured in coulombs (C)

number of electrons/protons is n, it is measured in numbers

electronic charge is e, it has a standard value = 1.6×10 −19

Coloumbs (C).

Equating both the above equations, that is, It = ne we get,n= e I×T = 1.6×10 −19 1×16 =10

20

Hence, number of electrons passing through a cross section of the filament in 16 seconds would be roughly 10 20.

Question 4:- A student carries out an experiment and plots the V-I graph of three samples of nichrome wire with resistances R1, R2 and R3 respectively (Figure 5). Which of the following is true?

(a) R1 = R2 = R3

(b) R1 >R2 >R3

(c) R3 >R2 >R1

(d) R2 >R3 >R1v⤵

Answer 4:- ⤵

Using the relation [R=V/I] , which is inverse of the tangent of the given graph.

As tangent of first is greater than second which is further greater than third, the order of resistance will be [R > R > R. ]

. [ 3. 2. 1. ]