In wireless sensor networks, devices are required to self-organize themselves into a network without previously established infrastructure. Because the device is battery-powered, one of the most important design criteria for this type of network is energy efficiency. Based on two linear traffic models and an extension of energy model of the radio, we consider different multi-hop scenarios to compute the energy and energy efficiency of the whole network. Through analyzing these results, we present two valid deployment mechanisms for sensor nodes.The first deployment mechanism is that nodes are deployed with equidistant spacing. Under this topology, we compute energy per payload bit, energy efficiency, and the total energy consumed by individual nodes, and the whole network. Simulation results show that a single-hop strategy is more efficient than a multi-hop one, especially for low path loss exponents, when the total distance is less than the feasible range of the radio. The receive and startup energy overhead, in addition to the energy drain increase at nodes close to the sink, makes multi-hop an inefficient technique. If overheads can be reduced with new transceiver technologies, multi-hop becomes more attractive.We derive the optimum value for one-hop spacing for the first mechanism, and present the formula to calculate the optimal value with the different application parameters. It is independent of the physical network topology, the number of transmission sources, and the total transmission distance. It only depends on the propagation environment and the device parameters. This mechanism can minimize the energy consumption of the whole network.The first deployment mechanism can achieve minimized energy consumption for the multi-hop scenario where each node transmits a data frame to the sink. However, it brings up a question of energy consumption disproportion between nodes. It is because those nodes close to the sink will relay larger amounts of data packets and their energy consumption will be more. In my intuition, node spacing is chosen shorter to consume less energy for the node closer to the sink. This strategy can balance energy consumption between nodes. So another deployment mechanism is that nodes are deployed with optimal spacing. We present the formula to calculate the optimal spacing. This mechanism can balance every node's energy consumption, thus prolonging the whole network's lifetime. Simulation results show that two deployment mechanisms are good and useful with energy efficiency in wireless sensor networks.