ALL CIE PHYSICS DOUBTS HERE !!!

[ashwinkandel]

Q4. The diagram shows two circuits which could be used to act as a dimmer switch for a lamp.
a. Explain one advantage circuit 1 has over circuit 2. [2]
b. One problem with circuit 1 is that there is always a current in the resistor. Explain how this problem could be rectified. [2]
c.
i. The lamp is rated at 60W at 240V. Calculate the resistance of the lamp filament at its normal operating temperature. [2]
ii. State and explain how the resistance of the filament at room temperature would compare with the value calculated in c i. [2]

[astarmathsandphysics]

Few mins

[astarmathsandphysics]

a)a wider range of voltage can be across the lamp
b) put a diode between the resistor and the bottom junction
c)P=V^2/R
60=240^2/R so R=240^2/60=960 ohms
It will be lower since resistance decreases with decreasing temp

[ashwinkandel]

@astarmathsandphysics Can you help me out with previous questions..(q no. 1 ,2 and 3) which are on the previous page.. and one more thing how putting the diode can solve that thing.

[astarmathsandphysics]

By putting a diode in the circuit no current will flow in the resistor when the connection is made at the top end.

[astarmathsandphysics]

Sorry I missed them. Here they are.

[cs]

why is the answer ytterium?  


and the next attachment, i dont get why is Krypton-90 placed after "S"

and need explanation for the 3rd attachment,

what is the "proper" working for attachment 4

thank you

[ashwinkandel]

Q. A student connects a high-resistance voltmeter across the terminals of a battery and observes a reading of 8.94 V. He then connects a 12ohm resistor across the terminals and finds that the potential difference falls to 8.40V.
b. Explain why the measured voltage falls.[2]
c.i. Calculate the current in the circuit.[2]
ii. Calculate the internal resistance of the cell.[2]
iii. State any assumptions you made in your calculations.[2]

[astarmathsandphysics]

Will do these in morning.

[astarmathsandphysics]

The answers to the scanned questions above

[astarmathsandphysics]

Ashwinkandel your answers attached

[cs]

Thanks for your time, download and see it in a while

another doubt i have, part c

[ashwinkandel]

Electricity

Q1. Figure 13.17 shows a circuit used to monitor the variation of light intensity in a room.
a. Identify the component X and describe how the circuit works.
b. Suggest the reason for including the variable resistor in the circuit.

Q2. The diagram shows a potential divider. The battery has negligible internal resistance and the voltmeter has infinite resistance.
a. State and explain how the reading on the voltmeter will change when the resistance of the variable resistor is increased.
b.Resistor R2 has a resistance of 470 ohm. Calculate the value of the variable resistor when the reading on the voltmeter is 2.0V
c.The voltmeter is now replaced with one of resistance 2Kohm. Calculate the reading on this voltmeter.
d. R2 is replaced with a light dependent resistor. Explain how the reading on the voltmeter changes as the light levels are reduced.

Waves
Q1.The diagram shows the traces of two sound waves displayed on an oscilloscope screen.
i. Explain whether or not the waves are in phase.
P.S: When are waves said to be in phase?
ii. State how their wavelength compare.
iii. Calculate the ratio of the intensities of the two waves

[astarmathsandphysics]

Shortly

[astarmathsandphysics]

see attachments