<p>Physics 12 Name: ______Version 1</p><p>Electric Fields and Potential Unit Test</p><p>Part A: Multiple Choice (2 marks each)</p><p>(1) What are the units of electric field strength? </p><p> a. N/C b. V/m c. both a. and b. d. neither a. nor b. </p><p>(2) What is the magnitude and direction of the electric field at point P?</p><p>4 4 a. 2.4 x 10 N/C left b. 2.4 x 10 N/C right 4 4 b. 3.0 x 10 N/C left d. 3.0 x 10 N/C right</p><p>5 (3) The electric field 20 mm from an unknown charge has a magnitude of 1.0 x 10 N/C. The magnitude of the electric field 10 mm from the charge is:</p><p>5 5 a. 4.0 x 10 N/C b. 2.0 x 10 N/C 4 4 c. 5.0 x 10 N/C d. 2.5 x 10 N/C</p><p>6 (4) A proton is accelerated from rest through a 1.0 x 10 volt potential difference. What speed does the proton attain?</p><p>4 7 a. 1.4 x 10 m/s b. 1.4 x 10 m/s 7 14 c. 1.9 x 10 m/s d. 1.9 x 10 m/s</p><p>(5) An electron accelerated in a vacuum through a potential difference of 'V' acquires a speed of 'v'. What speed does it acquire if the potential difference is '4V'?</p><p> a. 16 v b. 4 v c. 2 v d. v 2 (6) The potential difference between two parallel conducting plates is 8.7 x 10 V and –5 their separation is 0.400 cm. Find the work necessary to move 3.2 x 10 C of positive charge from the negative to the positive plate.</p><p> a. 0.0278 J b. 0.0295 J c. 6.95 J d. 2.78 J </p><p>-17 (7) A proton with kinetic energy of 2.1 x 10 J is moving into a region of charged parallel plates. The proton will be stopped momentarily in what region?</p><p> a. Region K b. Region L c. Region M d. Region N</p><p>(8) An electron moves from the negative plate to the positive plate in the situation shown below. It moves ______of the electric field and experiences a ______in potential energy.</p><p> a with the direction ; gain b. with the direction ; loss c. against the direction ; gain d. against the direction ; loss</p><p>Part B: Written Questions </p><p>(1) The nucleus of a helium atom contains 2 protons. An electron orbits the nucleus at a point 4.0 nm away. What is the magnitude and direction of the electric field at the location of the electron? (3 marks)</p><p>6 (2) An electron moving at 7.5 x 10 m/s enters an electric field between parallel plates by passing through a small hole in one of the plates as shown. </p><p> a) What is the impact speed on the second plate? Ignore friction. (4 marks)</p><p> b) If the plates are moved closer together, and the electron is released through again, will its impact speed be the same, greater, or less? ______(1 mark)</p><p> c) Explain using principles of Physics (2 marks). (3) A small 0.0021 kg plastic ball is suspended by a string in a uniform electric field as shown. Calculate the charge on the ball (4 marks)</p><p>(4) A helium nucleus having twice the charge and four times the mass of a proton is traveling with a high velocity when it enters a set of charged plates as shown.</p><p>What is the magnitude and direction of the acceleration of the nucleus? (4 marks)</p><p>6 BONUS: The plates are 1.0 m long and the nucleus enters at 1.5 x 10 m/s. What is the deflection of the helium nucleus just before it exits the plates? (1 mark)</p>