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• # Difficult Questions From Physics Jamb 2004

Physics

28-01-2016 12:03:00 +0000

These questions presented a challenge for most of the students that attempted them. Lets all attempt to answer them.

(Question 26) In a reverse biased junction diode, current flows in by.........?
A. Electrons alone
B. Majority carriers
C. Minority carriers
D. Positive holes alone

(Question 33) The change in volume when 450kg of ice is completely melted is?
[density of ice = 900 kgm-3, density of water = 1000 kgm-3]
A. 0.5m3
B. 0.45m3
C. 0.05m3
D. 4.50m3 UPDATE - ANSWER INCLUDED BELOW A big thank you to all that have participated in solving these questions. Though no one got the right answer it's encouraging to see you attempt to solve them. Here is a detailed breakdown of the solution for each of the questions above.

(Question 33).
The correct answer is C EXPLANATION
When you here the word change it implies difference.
So change in volume V = Volume of ice Vi - Volume of water Vw.
Now our work is to find the volumes of ice and water.
From formula, Density=mass/volume
Then volume by subject formula = mass/density.
For ice Vi = mass of ice/density of ice = 450/900 = 0.5m3
For water Vw = mass of water(which is same with ice)/density of water = 450/1000 = 0.45m3
Therefor change in volume V = 0.5m3 - 0.45m3 = 0.05m3

(Question 26).
The correct answer is C EXPLANATION
For reverse bias junction diode, the negative terminal of the battery is connected to the P-type material, and the positive terminal of the battery to the N-type material.

The negative potential attracts the holes (which are positively charged) away from the edge of the junction barrier(P-N junction) on the P side, while the positive potential attracts the electrons (negatively charged) away from the edge of the barrier on the N side. This action increases the barrier width because there are more negative ions on the P side of the junction, and more positive ions on the N side of the junction. This increase in the number of ions prevents current flow across the junction by majority carriers. However, the current flow across the barrier is not quite zero because of minority carriers crossing the junction.

• David Johnson

33 d

0 28-01-2016 12:07:00 +0000

• Prettyhajia Opeyemi

Show ur working

0 28-01-2016 12:53:00 +0000

• Abonyo crystal

0 28-01-2016 14:07:00 +0000

• Precious Johnson

26 d

0 28-01-2016 15:36:00 +0000

• chima valentine

b

0 28-01-2016 22:45:00 +0000

• Dami Yayo

26 b

0 28-01-2016 23:30:00 +0000

• Kizito Onyeagusi

33 (0.5m cube) the answer is not there

0 29-01-2016 09:01:00 +0000

These posts have been updated with the correct answers and their solutions. Check it out.

0 29-01-2016 14:20:00 +0000

• Dr Phalaye

tnx a lot jhutnxd

0 04-02-2016 19:10:00 +0000

• Chimezie Victor

Diedo is a device that carries Current in an opposite direction. So the answer is C

0 04-02-2016 19:17:00 +0000