Physics Mock Exams SS 3

PHYSICS

1. Arrange the following electromagnetic waves in their increasing order of wavelength, Infra-red rays, visible rays, radio waves and x-rays.(a) Radio waves, infra- red ray, visible rays, x-rays (b) x-rays, visible rays, infra –red rays, radio waves (c) Visible rays, x –rays, radio waves, infra-red rays. (d) Infra-red rays, Radio waves, X- rays, Visible rays.

1. 2. Which of the following radiation is of nuclear origin?(a) X- rays (b) Visible –rays (c ) Radio waves (d) Gamma rays.

2. 3. Which of the following radiations is found useful by soldiers fighting in darkness.(a) Gamma-rays (b) x- rays ( c) infra- red rays (d ) ultra violet rays.

3. The velocity of light in vacuum is

a. (a) 3. 0 x 106 m/s (b) 3.0 x 107 m/s (c) 3.0 x 108 m/s (d) 3.0 x 109 m/s

4. Which of the following has the shortest wavelength?

a. (a ) Radio waves (b) x –rays ( c) Infra –red rays (d) microwaves.

5. What is the gravitational potential due to a molecule of mass m at a distance r from it.?

a. (a) Gm (b) Gm (c) Gm2 (d) m2

b. r2 r r Gr2

6. Calculate the escape velocity for a rocket fired from the earth’s surface at a point where the acceleration due to gravity is 10m/s2 and the radius of the earth is 6.0 x 106m

a. (a) 7.8 x 103m/s (b) 1.1 x 104m/s (c ) 3.5 x 107m/s (d) 6.0 x 107m/s

7. 3. If g = 9.8m/s2. G = 6.7 x 10-11Nm2kg-2, calculate the mass of the earth if the radius is 64000km. (a)6.14 x 1023kg (b) 5.99 x 1024kg (c ) 3.98 x 1026kg (d ) 4.02 x 1025kg

3. Two objects of mass 80kg and 50kg are separated by a distance of 0.2m. calculate the gravitational attraction between them if G = 6.67 x 10-11 Nm2kg-2.

a. (a) 6.67 x 10-6 (b) 6.67x 106N (c) 5.92 x 10-6N (d) 5.92 x 106N.

4. Which of the following statements is/are correct about gravitational potential?

i. V = -Gm

ii. r

I. The negative sign indicates that work done is against the gravitational field.

II. The potential at infinity is zero

III. The potential at infinity is less than that at the surface of the earth.

IV. Gravitational potential is a vector quantity

b. (a)I and II only (b) III and IV Only (c) III only (d) I,II and III only (e) II and IV only.

c. Calculate the force acting on an electron carrying a charge of 1.6 x 10-19C in an electric field of intensity 5.0 x 108 N/C is (A). 3.2 x 10-29N (B).8.0 x 10-11 (C). 3.1 x 1027N D. 4.6 x 10-6N

8. 2. Find the electric field intensity in a vacuum at a distance of 10cm from a point charge of 15uc if 1/ 4πε0= 9.0 x 109(A). 1.35 x 107NC-1(B). 1.4 x 1010NC-1(C). 1.3 x 1011NC-1 (D).1.5x1010NC-1

9. 3. Which of the following statements is/are true about an isolated positively charged sphere? I. It contains excess positive charges.II.It has an electric field associated with it. III. It carries electric current. Iv. It has excess negative charges.A. I and II only B. I, II and III only

C. II and IV only D.III and IV E. I and III only

5. Two capacitor of capacitance 3uF and 6uF are connected in series. Calculate the equivalent capacitance (a) 9uF (b) 6uF (c) 2uF (d) ½ uF.

6. A capacitor stores 10-4c of charge when the p.d between the plates is 1kv. What is the capacitance? (a) 10-4uF (b) 0.1 uF (c) 4uF (d) 100uF.

10. Which of a-d below is correct?(i)Ordinary torch battery is an example of primary cell.(ii) Accumulations have very high interne resistance.(a)(i) only (b) (ii) only (c)(iii) only (d) (i) and

(ii) only

11. Which of the following statement is not true? (a) The chemical action in a primary cell is irreversible (b) Lead-acid accumulation can be recharged (c) Lead-acid accumulator has large internal resistance (d) A secondary cell can be recharged

12. The defect in simple cell which result in a back e.m.fand increase in internal resistance is known as (a)local action (b) reduction (c)polarization (d) oxidation

13. Which of the following instrument is most accurate for comparing e.m.f of two cell? (a) Wheatstone bridge (b) galvanometer (c) potentiometer (d)meter bridge

14. Which of the following devices coverts mechanical energy to electric current? (a) Battery (b) Photocell (c) Thermopile (d) Dynamo

15. The internal resistance of each of the cells E1 and E2 shown in the figure below is2 Ω. Calculate the total current in the result (A) 0.80a (B) 0.50a (C) 0.40a (d) 0.004a

16. A cell of e.m.f 1.5V and internal resistance 2.5pohms is connected in series with an ammeter of resistance 0.5 ohms and a resistor of resistance 0.7ohms. Calculate the current in the circuit. (a) 0.15A(b) 0,20 A (c) 0.60 A (d) 3.00A (e) 6.67A

17. A cell of internal resistance 2 ohms supplies a current of a 6-hm resistor. The efficiency of the cell is (a) 12.0% (b) 25.0% ( c) 33.3% ( d) 75.0%

18. When a resistance r is a across a cell, the voltage across the terminals of the cell is reduced to two-thirds of its nominal value. The internal resistance of the cell is (a) 1/3R (b) ½R (c)2/3R (d) R

19. Which of the following does not determine the electrical resistance of a wire? (a) Length (b)

Color (c) Cross-sectional area (d) Temperature

20. An iron ore which attracts pieces of iron to itself is called —(A) iron (B) steel (C) lodestone (D) cobalt

21. The following are magnetic substances except —(A) cobalt (B) Nickel (C) iron (D) brass

22. The end of a solenoid where current flow is clockwise represents—(A) north pole (B) neutral pole (C) south pole (D) magnetic equator

23. A magnetic substance can be demagnetized by —(A) dropping on the floor. (B) hammering while red hot. (C) divided touch. (D) single touch.

24. The following are alloys for making powerful magnets except —(A) alcomax (B) alnico (C) mumeta(D) ticonal

25. Alloys for making powerful permanent magnets are these except — (a) alcomax (b) alnico

(c) mumetal(d) ticonal

2. A magnetic substance can be demagnetized by (a) dropping on the floor (b) hammering while hot (c) divided touch (d) single touch

26. 3. Which of the following pairs of metals will be picked up by an electromagnet? (a)Aluminium and Copper (b) Brass and Copper (c) Iron and Steel (d)Aluminium and Brass

27. 4. Which question can be asked to determine if a material is magnetic or non-magnetic?

(a) Is it a metal or a non-metal? (b) Is it a conductor or an insulator? (c) Is it a solid or a gas (d)Does it affect the direction of a compass needle?

28. 5. One of the following rules can be used to determine the direction of the magnetic field around a straight current carrying conductor. (a) Fundamental law of magnetism(b) Clenched fist rule (c) Fleming’s right hand rule (d) Fleming’s left hand rule

THEORY

1. State Maxwell’s cork screw rule.

2. Draw the diagram showing the magnetic field around a solenoid.

THEORY

1. Explain the term magnetic fields

2. State and explain three properties of a magnet.

THEORY

1. A battery of three cells in series, each of e.m.f. 2 V and internal resistance 0.5 Ω is connected to a 2 Ω resistpr in sries with a parallel combination of two 3Ω resistors. Draw the circuit diagram and calculate

a. the effective external resistance

b. the current in the circuit

c. the lost volts in the battery

d. the current in one of the 3 Ω

2. Calculate the length of a constantin wire of diameter 0.6 mm and resistivity 1.1 x 10-6Ωm required to construct a standard resistor of resistance 35Ω

THEORY

1. Briefly differentiate between primary cell and secondary cells.

2. In electrolysis of copper tetraxosulphate (vi) using copper electrodes, 1.53g of copper wire deposited in 30 minutes. Determine the average current used.(Z=3.29 x 10-4)

THEORY

1. If three charges are distributed as shown in the diagram below.

+10C 3m

– 20C

2m

+16C

Find the resultant force on the +10C charge (take 1 = 9.0 x 109s.I. units)

4πEo

2. Two charges of +5uc and -10NC are separated by a distance of 8cm in a vacuum as shown below.

+5uc B -10uc

Calculate the magnitude and direction of the resultant electric field intensity due to point B. 1/ 4πEo = 9.0 x 109 s.I unit.

THEORY

1. The average radius of Jupiter’s orbit round the sun of mass 2 x 1030Kg is 7.8 x 1011m. If the mass of Jupiter is 1.9 x 10 27, find the gravitational force the sun exerts on Jupiter , G = 6.67 x 10-11Nm2kg-2

2. If the mass of a portion is 1.67 x 10-27kg and the mass of an electron is 9.11 x 10-31kg, calculate the force of gravitation between:

i. a proton and an electronii. two electronsiii. two protons.

Take G= 6.67 x 10-11 Nm2kg-2, distance between the protons = 4.0m., distance between the electrons = 2 x 10-2m, distance between the proton and the electron = 5.4 x 10-11m

THEORY

1. (a) What rays make up the radio waves?

(b) Arrange these radiations in their increasing order of wavelength.Ultraviolet rays,Radio waves Visible spectrum, Infra-red wavesX- rays Gamma –rays

2. (a) What is a radar?

(b) What type of electromagnetic radiation does it use?

(c) How does it function?