Waec Physics 2010 Past Questions and Answers

Question 66:

• WAEC 2010

(a)

When a positively charged conductor is placed near a candle flame, the flame spreads out as shown in the diagram above. Explain this observation.
(b) A proton moving with a speed of 5.0 x 10${}^5$ ms${}^{-1}$ enters a magnetic field of flux density 0.2 T at an angle of 30° to the field. Calculate the magnitude of the magnetic fcrce exerted on the proton. [Proton charge = 1.6 x 10${}^{-19}$ C]
(c)

The diagram above illustrates a 9.0 V battery of internal resistance 0.5 $\mathrm{\Omega }$ connected to two resistors of values 2.0 $\mathrm{\Omega }$ and R $\mathrm{\Omega }$. A${}_1$ A${}_2$ and A${}_3$ are ammeters of negligible internal resistances. If Al reads 4.0 A, calculate the:
(i) equivalent resistance of the combined resistors 2.0 $\mathrm{\Omega }$ and R $\mathrm{\Omega }$;
(ii) currents through A${}_1$ and A${}_3$ ; (iii) value of R.