ATAR Notes: Forum
VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Physics => Topic started by: knightrider on February 12, 2014, 09:38:10 pm
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hi can anyone help with these questions even my teacher doesn't know the answers',and can you please show full working and explanation
1 A charge of +q is placed a distance r from another charge also of +q. A repulsive force of magnitude F is found to exist between them. Describe the changes, if any, that will occur in the force when:
a) one of the charges is doubled to +2q
b) both charges are doubled to +2q
c)one of the charges is changed to −q
d)the distance between the charges is changed to 1/ 2r.
2) Danielle and Daniel set up two Van de Graaff machines exactly 80 cm apart (centre to centre) on frictionless trolleys that allow them to measure the force between them. They read that the manufacturer states that it is possible to obtain a charge of 5 µC on the domes of the machines and then proceed to use Coulomb’s law to calculate the force they expect to find between them.
a) What force do they expect to find between the machines?
b) Assuming that the charge on each machine is 5 µC, why do they find that the measured force is less than they expect?
3) Some small charged spheres are to be placed in an elec tric field which points downwards and has a strength of 5000 N C−1.
a) What force would be experienced by charges of +2 µC and −5 µC?
b)A sphere with an unknown charge is found to experience an upwards force of 1 × 10−3 N in this field. What was the charge on the sphere?