SS 3 Physics 2ND TERM

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SS 3 Physics 2ND TERM

Section A

1. A 50Hz a.c circuit has a voltage of 220V and a current of 5.0A as its effective value. Determine the peak values of the voltage and its current. (a)311.0V and 1.71A (b) 331.0V and 7.10A (c) 311.00V and 7.10A(d)7.10V and 311.00A
2. Calculate the peak voltage of a mains supply of r.m.s value of 220V. (a)112V (b) 150V (c) 222V (d) 311V
3. In an ac circuit the peak value of the potential difference is 180V. what is the instantaneous potential differences when the phase angle is 45o. (a)45V (b) 90V (c) 90√2 V (d)180V
4. An ammeter connected to an a.c circuit records 5.5A. What is the peak value of the current? (a) 7.8 (b) 7.1 (c) 3.9 (d) 3.
5. A 2µF capacitor is in series with a resistor of 5000Ω. A voltage of 5V r.m.s and frequency, I= 100Hzis connected to them. What is the capacitive reactance?
(a) 795.5Ω (b) 895.5 Ω (c)1795Ω (d) 2005.0Ω
6. At what frequency will 20uf capacitor have a reactance of 500 ohms?
(a) 100Hz (b) 50Hz (c) 150Hz (d) 100π Hz (e) 30Hz
π π π π π
7. In an RLC series a,c circuit power is dissipated in (a) Resistance only (b) Reactance only (c) Resistance and reactance (d) Resistance, inductance and capacitance
8. In a series L-C circuit, the inductance and the capacitance are 0.5H and 20µF respectively. Calculate the resonance frequency of the circuit (a) 24.2Hz (b) 36.7Hz (c) 50.3Hz (d) 60.5Hz
9. Which of the following statement is not true of the isotope of an element? They A. Are atoms of the same element B. Have the same chemical properties C. Have the same atomic mass D. Have the same mass number
10. Which of the following representation is correct from an atom X with 28 electrons and 30 neutrons? A. 3028X B 2830X C 5830X D. 5828X E. 302X
11. Bohr theory provides evidence for the A structure of the atom B. positive charge of an electron C existence of energy level in the atom D. positive charge on a proton
12. Which of the following particles determine the mass of an atom? A. protons and neutrons
B. Neutrons only C. protons and electrons D. Neutrons and electrons E. Protons only
13. A radioactive substance has a half-life of 3 days. If a mass of 1.55g of this substance is left after decaying for 15days,dertermine the original value of the mass (A) 49.6g (B) 37.2g (C) 24.8g (D) 12.4g
14. Which of the following is usually used to cause fission in an atomic reactor? (A) alpha particles (B) beta particles (C ) electrons (D) neutrons
15. A substance has a half-life 30 mins after 6mins the count rate was observed to be 400. What was its count rate at zero time. (A) 200 (B) 1200 (C) 1600 (D) 2400
16. A nuclide 20284Y emits in succession an α-particle and β-particle. The atomic number of the resulting nuclide is (A) 198 (B) 83 (C ) 82 (D) 80.
17. The count rate of radioactive substances diminishes from 600 to 150 in 60 secs. Determine the half life of the substance (a) 15 secs (b) 30 secs (c) 45 secs (d) 60secs.
18. A radioactive substance half life of 20hrs. what fraction of the original radioactive nuclide will remain after 80hrs (a) 1/32 (b) 1/16 (c ) 1/8 (d) 15/16
19. A material of mass 1.0X10-3kg undergoes fission process which decreases its mass by 0.02%. calculate the amount energy released in the process [c=3X108m/s]
(A) 1.8X1020J (B) 1.8X1013J (C) 1.8X1011J (D) 1.8X1010J
20. In a nuclear reaction the mass defect is 2.0X10-6g. Calculate the energy released, given velocity of light is 3X108m/s. (A) 9.0X1007J (B) 1.8X1008J (C) 1.8X1009J (D) 9.0X10 10J
21. When an atom is in ground state, it is said to be (A) excited (B) stable (C) ionized
22. In which of the following transitions is the largest quantum of energy liberated by an hydrogen atom, when the electron changes energy level? (A) n=2 to n=1 (B) n=2 to n=3 (C) n=3 to n=2
(D) n=1 to n=2
23. Which of the following give rise to the line spectra obtained from atoms. (A) change of electron from a higher to lower energy level (B) potential energy of the electron inside an atom
(C ) Excitement of an electron in the atom
24. A 50KV is applied across an x-ray tube. Calculate the maximum velocity of the electrons produced. [Me= 9.11X10-31Kg, e= 1.6X10-19C] (A) 4.2X108m/s (B) 1.8X108m/s (C) 4.2X105m/s
(D) 1.8X105m/s
25. Which of the following is called photo electric effect. (a) two electrons are created from a quantum of light (b) metals absorbs quanta of light and then emits electrons (c) a high energy
emits photon as it is slowed down
26. The minimum frequency that can cause photo emission of electrons from metal surface is known as (a) wavelength (b) threshold frequency (c) frequency of the incident light
27. The maximum kinetic of the photo electrons depend on (a) work function (b) frequency
(c) intensity of the incident ray
28. The minimum energy required to liberate an electron from a metallic surface is (a) ionization energy (b) work function (c) kinetic energy,
29. The term electrical discharge means (a) voltage is a gas (b) current in a liquid ( c) current in a gas (d) voltage in a liquid.
30. Which of the following is an application of glow discharge phenomena? (a) filament lamp
(b) fluorescent lamp (c) cathode ray oscilloscope (d) electron microscope .
31. Which of the following is an application of hot cathode emission. (a) filament lamp (b) cathode ray oscilloscope (c) electron telescope (d) Binoculars
32. Which of the following contributed to conduction in a gas? (i) molecules (ii) electrons (iii) ions (A) I only (b) II only (c) I and III only (d) II and III only.
33. Which of the following are not complimentary variables (a) Energy and time (b) energy and position (c) Energy and mass (d) Velocity and position .
34. The duality of matter implies that matter? (a) Exist as particle of dual composition (b) has momentum and energy (c) has both wave and particle property (d) is made up of dual materials
35. According to quantum theory, electromagnetic wave is transmitted in tiny bundles of energy called (a) photons (b) electrons (c) photons (d) protons
36. Which of the following scientists proposed the uncertainty principle? (a) De Broglie
(b) Heisenberg (c) Newton (d) Lenz
37. The following are components parts of a rocket except (a) fins (b) nozzle (c) propellant tank
(d) turbine.
38. One of the following is a component of a satellite (a) camera (b) fins (c) command antenna
(d) solar cells.
39. The function of the fins in a rocket is to (a) beautify it (b) make it fly (c) stabilize it and maintain its direction of motion (d) increase its mass.
40. What is the function of the power generation and distribution system in a satellite?
(a) capturing solar energy and converting it to the electrical energy needed (b) increase the weight of the engine (c) receiving and transmitting of data (d) to beautify the satellite.

Section B

1. What are satellites used for?
I. What are the functions of: (i) the hot filament (ii) the anode (iii) fluorescent screen
II. What is thermionic emission.

2. Determine the frequency of the photon whose energy is required to eject a surface electron with a kinetic energy of 1.970 x 10-19 eV. If the work function of the metal is 1.334 x 10-19eV.(1eV = 1.6 x 10-19J, h = 6.6 x 10-34Js, C = 3 .0 x 108ms-1)

3. An electron jumps from one energy level to another in an atom radiating 9.0×10-19J. If h = 6.6 x 10 -34Js and C = 3.0 x 108m/s, what is the wavelength, and the frequency of the radiation.

4. Explain the terms nuclear fission and nuclear fusion
I. A nuclide X emits β-particle to form a daughter nuclide Y. write a nuclear equation to illustrate the charge conservation.
II. The isotope of a nuclide has a half-life of 5.4X103s.Calculate its decay constant.

5. What are the essential features of the Electron –Cloud Model of the atom. Illustrate with a diagram.

6. Draw a vector diagram of the relationship of I and V for an a.c. circuit containing
(a) a pure inductor (b) a pure capacitor (c ) a pure resistor

7. Distinguish between alternating current (a.c) and direct current (d.c). Explain the term peak value and r.m.s. value as they apply to a.c circuit