2021-PA-Physics 2A Practical A

Objectives: Physics 2A Practical A 2021

Physics 2A Practical A

THE UNITED REPUBLIC OF TANZANIA

NATIONAL EXAMINATIONS COUNCIL OF TANZANIA

CERTIFICATE OF SECONDARY EDUCATION EXAMINATION

031/2A — PHYSICS 2A (PRACTICAL A)
Time: 2:30 Hours • Year: 2021
  • This paper consists of two (2) questions. Answer all questions.
  • Each question carries twenty five (25) marks.
  • Non‑programmable calculators may be used.
  • Cellphones and unauthorised materials are not allowed in the examination room.
  • Write your Examination Number on every page of your answer booklet(s).

1) Compound Pendulum Experiment

You are provided with a thread, a pendulum bob, a wooden rod, and a retort stand as shown in Figure 1. Follow the procedure then answer the questions.

Figure 1: Experimental setup
Bench/Table Retort stand Wooden rod Pendulum bob N Thread
Procedure
  1. Tie a thread to the pendulum bob. Fix a wooden rod as shown in Figure 1 and mark its reach point N on the thread. Then remove the rod.
  2. Measure a distance a = 20 cm from point N to the point of suspension. Displace the bob slightly and release so it performs to-and-fro motion. Determine the time, t, for 20 oscillations and hence the period T = t/20.
  3. Repeat for a = 40, 60, 80, 100 cm.
Results Table
Trial a (cm) t for 20 oscillations (s) T = t/20 (s) T2 (s2)
120
240
360
480
5100
Tip: compute T by dividing t by 20, then square to get T2.
Analysis

Plot a graph of T2 (s2) against a (cm).

From the straight-line relation T2 = S(a + b), determine:

  • the slope S of the graph,
  • the intercept parameter b, and
  • state what the value of b represents physically.

2) Electrical Measurements — Cells, Rheostat, Ammeter & Voltmeter

You are provided with two dry cells of e.m.f. E, a key K, a rheostat Rh, an ammeter A, a voltmeter V, an unknown resistor R and a 4 Ω resistor.

Figure 2: Circuit diagram
E K Rh A R 4 Ω V V R 4 Ω
Procedure
  1. Set up the circuit as in Figure 2.
  2. Close the key and adjust the rheostat so the ammeter reads 0.1 A. Record the voltmeter reading V (volts).
  3. Repeat for ammeter readings of 0.3, 0.5, 0.7, 0.9 A.
Results Table
Trial I (A) V (V) 1/I (A-1) 1/V (V-1)
10.1
20.3
30.5
40.7
50.9
Analysis
  1. Plot a graph of 1/I against 1/V.
  2. Find the slope of the graph.
  3. Determine the value of the unknown resistance R.
  4. State the effect of connecting the 4 Ω resistor R4Ω as shown (i.e., in parallel with R).

Reference Book: N/A

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