Qualification > Sciences
Maths & Physics Help
hyebyekadal:
Now I am lost....
Zain-Xa:
i got the first part by i dont get wt u divide by 2 to get the remainder 3... etc. ???
godfather93:
example - suppose a bulb is connected to a power source. Nothing else except for the bulb and the connecting wires to the power supply. Now let us add a resistor into the circuit (in series). you will notice the bulb gets dimmer. Why is it? Its because the resistor is using up some of the battery's voltage, thus, decreasing the voltage supplied to the bulb (you probably know that a bulb's brightness decreases whe the voltage decreases). Now, instead of the resistor, add a variable resistor. As you increase the resistance, the bulb gets dimmer. More voltage is being used up by the variable resistor and less of the voltage from the battery is reaching the bulb.
Hopefully you get it now.
astarmathsandphysics:
--- Quote from: hyebyekadal on May 09, 2009, 08:28:31 pm ---Guys one more question !!!
Q 36 in the attached paper why is the correct answer D? Shouldn't it be C? When the resistance increases whys does the p.d. increase?
Again thanks in advance!!
Opps! Forgot to upload paper! Here!
--- End quote ---
The answer is D We have a potential divider. The LDR is a semiconductor and the resistance goes up in the dark because less electrons move into the conduction band. VLDR=VRLDR/(R+RLDR) and VLDR increases with |RLDR
Zain-Xa:
plllzz answer my question :'(
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