The document contains a physics homework assignment with 8 questions covering topics like light reflection, speed calculations, circuit analysis, electrical power calculations, unit conversions, and comparing numerical values. The questions involve drawing ray diagrams, calculating speeds, determining current and potential differences in circuits, performing unit conversions between standard and scientific notation, and identifying the larger of two numerical values.

1. BRIGHT START FELLOWSHIP INTERNATIONAL SCHOOL
Grade : IX Subject : Physics VacationHW 05.05.2011
Name : ___________________________
1. The two mirrors are now moved so that they are at exactly 30° to each
other. The incident ray is parallel to one of the mirrors.
in c id e n t
ra y
30º
Draw the path of the ray of light on the diagram. Use a ruler and a protractor.
Label the emergent ray and draw an arrow to show its direction.
2. A video recorder is loaded with a tape which plays for 180 minutes.
The length of the tape is 260 m.
(a) (i) Calculate the speed of the tape, in metres per minute.
____________________________________ m/min
(ii) What is the speed of the tape in metres per second?
_____________________________________ m/s
(b) To rewind the tape quickly, a different motor is used, which rewinds the
tape at a maximum speed of 1.08 m/s.
(i) At this speed, how long would it take to rewind the tape
completely? Give the units.

2. 3. Fill in the following blanks with the words electrons or protons.
____________________ are negatively charged and ____________________ are
positively charged. The ____________________ reside in the nucleus of atoms
and are tightly bound; they will never leave an atom as a result of electrostatic
procedures. On the other hand, ____________________ are located outside the
nucleus and are easily removed from or added to atoms. As an object begins to
gain or lose ____________________ from its atoms, it becomes positively or
negatively charged. A negatively charged object has more ___________________
than ___________________. A positively charged object has more
__________________ than __________________.
4. (a) Teresa set up the circuit shown in the diagram. The ammeter reading was
0.4A.
(i) What is the value of the current through the 4Ω resistor?
(ii) What is the value of the current through the 6Ω resistor?
(b) Calculate:
(i) the potential difference across the 6Ω resistor.
(ii) the potential difference across the 4Ω resistor.

3. (c) A third resistor is placed in series with the 4Ω and 6Ω resistors. The total
resistance of 3 resistors in series is given by: Rtotal = R1 + R2 + R3. The current
now falls to 0.25 A. Calculate the value of the third resistor.
5. (a) An electric kettle has a power rating of 2.4 kW.
(i) Using the equation: Power (W) = energy transferred / time
calculate the electrical energy used by the kettle in 1 minute.
(ii) Not all the energy supplied by the mains goes into heating the water. What
happens to it?
(b) (i) Power is also given by the equation: Power (W) = p. d. × current
Calculate the current flowing the the electric kettle element. (mains voltage
is 240 V)
(ii) Name 2 other appliances in the home that convert electrical energy to mainly
heat energy.
______________________________________________________________
______________________________________________________________

4. 6. Write the following values using the appropriate multiple or submultiple.
Remember to observe the units involved.
e.g. 23,000 Ω in its shortest form = 23 KΩ
(a) 360,000 W
(b) 8.8 x 10-6 A
(c) 2.7 x 103 Ω
(d) 0.000,01 V
(e) 0.000,000,22 F
(f) 4,700,000 Ω
(g) 0.000,0068 A
7. Write the following values without using any multiples or sub-multiples,
and then in standard form.
e.g. 6.8KΩ = 6,800 Ω = 6.8 x 103 Ω
(a) 3.3KΩ
(b) 4.7 MW
(c) 12 mA
(d) 470 pF
(e) 50 µV
(f) 22.5nA
8. Write down the largest value from each pair:
2,650 W or 26.5 KW
0.000,000,044 A or 4.4 x10-9 A
0.000,01 V or 1 µV
3.3 x 103 KΩ or 33,000 Ω