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29-01-2016 12:13:00 +0000
Hello, today we will be looking at another physics questions from jamb 2004. These appears to be very tough questions. Our record shows that over 90% of test takers failed these questions.
Try solving these questions and see if you can answer them.
(Question 42) If 16mA of current flows through a conductor in one second, the number of electrons transported per second is.....?
[1 electronic charge = 1.6 x 10-19C]
A. 1.00 x 1020
B. 2.56 x 10-18
C. 2.56 x 10-17
D. 1.00 x 1017
(Question 43). The difference between x-rays and gamma rays is that
A. X-rays arise from energy changes in the electronic structure of atoms while gamma rays come from the nucleus
B. X-rays are electromagnetic radiations while gamma rays are negatively charges radiations.
C. X-rays have lower frequencies than gamma rays
D. X-rays are more penetrating than gamma rays
UPDATED- ANSWERS OF QUESTIONS ABOVE
Option D is the correct answer
recall from formula that charge(q) = it
where i = current
t = time
from question i = 16mA and t = 1s
therefore q = 16 x 10-3A x 1s = 16 x 10-3C
Now, 1 electron carries a charge of 1.6 x 10-19C
i.e 1 electron = 1.6 x 10-19C
? = 16 x 10-3C
Cross multiplying we have
? = 16 x 10-3/ 1.6 x 10-19
? = 10 x 10-3 + 19
? = 1017 electrons
where ? is the number of electrons
Option C is the correct answer.
From electromagnetic spectrum point of view, arranging in the other of decreasing frequency, Gamma rays top the field, followed by X- rays, Ultra violet, white light etc.
Differences between X−rays and Gamma−rays as
1. Gamma−rays cause more harm to human body than the X−rays.
2. Gamma−rays have shorter wavelengths than the X−rays.
3. X−rays are emitted by the electrons outside the nucleus, and gamma−rays are emitted by the excited nucleus itself.
4. X−rays are used in hospitals for taking X−rays but gamma−rays are not.