42. /12 мин./ Зафиксируйте время начала и окончания вы->4 полнения задания, а) Ознакомьтесь с текстом с целью понять его общее содержание.
Ohm’s Law & Resistance
1. The free electrons which contribute to the electric current have a low drift velocity in the negative direction of the field within the conductor.
2. In moving through the metal in a common general direction they enter into frequent collisions with the molecules of the metal, & as a consequence they are continually retarded in their forward motion & are not able to attain a velocity greater than axertain terminal velocity U, which depends on the value of the field & the nature of the substance.
3. The collisions which tend to reduce the drift velocity of the electrons act as a retarding force.
4. When a current is flowing, this retarding force must be exactly equal to the accelerating force of the field.
б) Проверку понимания текста осуществляйте следующим образом: для каждого из следующих трех предложений выберите правильное продолжение, мысленно обращаясь к тексту данного задания.
1. The free electrons which contribute to the electric current, have... a) a low drfft velocity in the positive direction of the field; b) a high drift velocity in the negative direction of the field; c) a low drift velocity in the negative direction of the field. 2. In moving through the metal in a common general direction the free electrons enter into frequent collisions with the molecules of the metal, & as a consequence... a) they are continuallyjetarded in this forward motion; b) they are able to attain a velocity greater than a certain terminal velocity U; c) they are able to attain the same velocity as a certain terminal velocity U. 3. The collisions which tend...act as a retarded force, a) to increase the drift velocity of the electrons; b) to reduce the drift velocity of the electrons; c) to depend on the value of.the field & the nature of the substance.
в) Накройте текст е пропущенными словами прозрачной пленкой. Учитывая контекст, восстановите в памяти эти слова и запишите их на "Пленку. Проверьте себя. Укажите количество правильно записанных слов.
1. The free electrons which... to the electric current...a low drift velocity...the negative direction of the...within the conductor. 2. In moving through the... in a common generaL.they enter into frequent... with the molecules of the..., as a consequence they...continually retarded in their...motion & are not...to attain a velocity...than a certain terminal...U, which depends on the... of the field & the...of the substance. 3. The collisions which tend to...the drift velocity oL.electrons act as a retarding... 4. When a current is..^, this retarding force must be exactly equal to the...force of the field.
