IB Physics Static Electricity
/A tutorial sheet on electroscope questions is given below
- A radioactive sample is placed inside a charged electroscope. Describe what happens to the leaves of the electroscope.(radiation ionises the air inside the electroscope creating ions which are attracted to the leaves reducing their net charge causing them to collapse gradually).
- A rod is brought near the cap of a positively charged electroscope. The leaves of the electroscope collapse and then diverge as the rod comes closer to the cap. Must the rod have a net negative charge? (yes, in this case the size of the charge on the rod is much greater than the size of the charge on the electroscope).
- An electroscope has a net positive charge. A rod is brought near the cap of the electroscope and the leaves continually diverge as the rod approaches. Must the rod have a net positive charge? (yes).
- A rod is brought near the cap of a positively charged electroscope. The leaves of the electroscope diverge when the rod is near the cap. Must the rod have a net positive charge? (no).
- What is the test for determining the relative sign of the charge on a charged electroscope and a rod? (observe the initial effect; if the leaves collapse they are oposite in sign,if they diverge they have the same sign).
- A charged body at first attracts an uncharged object. True or false? (True. When a charged ebonite rod is brought near small pieces of paper a charge of unlike sign is induced on the near side of the paper attracting them to the rod. When contact is made with the rod charge of like sign is transferred to the paper repelling it from the rod).
- An uncharged metal disc has a radius a. A point charge q is placed on the axis of the disk at a distance d from its centre. What is the magnitude of the electric force acting on the charge q?
- A metal disc of radius a has a charge Q. What work was done in charging this disc?
