Physics Past Questions and Answers

The bulb of a motorcycle head-lamp is marked 40W, 6V. The resistance of the filament when it is switched on is

A \(\frac{6^2}{40^2}\)ohms
B \(\frac{40}{6^2}\)ohms
C \(\frac{40}{6}\)ohms
D 6 x 40 ohms
E \(\frac{6^2}{40}\)ohms

Question 77:

In an electrolysis experiment, a cathode of mass 5g is found o weigh 5.01g after a current of 5A flows for 50 seconds. What is the electrochemical equivalent of the deposited substance?

A 0.00004g/C
B 0.00002g/C
C 0.02500g/C
D 0.05000g/C
E 0.00001g/C

Question 78:

Which of the following statements about radioactivity are true? i. alpha particle is positively charged ii. Beta particle is negatively charged iii. Gamma ray is neutral iv. Beta particle has the same mass as helium atom v. Gamma ray is charged

A I, ii, iii and iv only
B Iv and v only
C I, ii and iii only
D I, ii and v only
E All

Question 79:

Consider a thick glass tumbler and a thin glass tumbler which are made of the same kind of glass. Some hot liquid is poured into them. Which of the following statements is correct?

A The thick tumbler is less likely to crack because it is stronger
B The thick tumbler is less likely to crack because it insulates the heat beter, glass being a poor conductor of heat
C Both tumblers are equally likely to crack because they are made of the same kind of glass
D The thick tumbler is more likely to crack because uneven expansion persists for a longer time within the thicker glass
E The thick tumbler is more likely to crack because it is heavier

Question 80:

A capacitor and a resistor are connected in series with each other and in series with an accumulator of negligible internal resistance. The potential across the terminals of the capacitor is

A Twice the e.m.f of the accumulator
B Less than the e.m.f by the potential drop across the resistor
C Zero
D The same as the e.m.f.
E Greater than