【单选题】
电阻器反映导体对电流起阻碍作用的大小，简称___。
A. 电动势
B. 功率
C. 电阻率
D. 电阻
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相关试题
【单选题】
___反映了在不含电源的一段电路中，电流与这段电路两端的电压及电阻的关系。
A. 欧姆定律
B. 楞次定律
C. 部分电路欧姆定律
D. 全欧姆定律
【单选题】
并联电路中的总电流等于各电阻中的___。
A. 倒数之和
B. 相等
C. 电流之和
D. 分配的电流与各电阻值成正比
【单选题】
串联电路中流过每个电阻的电流都___。
A. 电流之和
B. 相等
C. 等于各电阻流过的电流之和
D. 分配的电流与各电阻值成正比
【单选题】
___的一端连在电路中的一点，另一端也同时连在另一点，使每个电阻两端都承受相同的电压，这种联结方式叫电阻的并联。
A. 两个相同电阻
B. 一大一小电阻
C. 几个相同大小的电阻
D. 几个电阻
【单选题】
___的电阻首尾依次相连，中间无分支的联结方式叫电阻的串联。
A. 两个或两个以上
B. 两个
C. 两个以上
D. 一个或一个以上
【单选题】
电流流过负载时，负载将电能转换成___。
A. 机械能
B. 热能
C. 光能
D. 其他形式的能
【单选题】
电功的数学表达式不正确的是___。
A. W=Ut/R2t
B. W=UIt
C. W=U2t/Rt
D. W=I2Rt
【单选题】
测量电压时，电压表应与被测电路___。
【单选题】
测量电流时,万用表的接线方法与直流电流表一样，应把万用表___在电路中。测量直流电压时，应把万用表与被测电路并联。
【单选题】
串联电路中各电阻两端电压的关系是___。
A. 各电阻两端电压相等
B. 阻值越小两端电压越高
C. 阻值越大两端电压越高
【单选题】
确定正弦量的三要素为 ___。
A. 相位、初相位、相位差
B. 最大值、频率、初相角
C. 周期、频率、角频率
【单选题】
当电压为5V时,导体的电阻值为5欧,那么当电阻两端电压为2V时,电阻值为___欧。
【单选题】
对称负载接成星形时,三相总电流___。
A. 等于零
B. 等于其中一相电流的三倍
C. 等于其中一相电流。
【单选题】
一段有源支路如图1所示，AB两端的电压UAB为___。
A. 10 V
B. —2V
C. 2V
D. —10V
【单选题】
如图2电路中，等效电阻=___
A. 150Ω
B. 900Ω
C. 600Ω
D. 100Ω
【单选题】
电流表的读数是4A，则电路中电流表的读数是 ___
【单选题】
在R、L、C串联电路中，已知＝3Ω，＝5Ω，＝8Ω，则电路的性质为 ___。
A. 感性
B. 容性
C. 阻性
D. 不能确定
【单选题】
工业生产中大量的设备均为感性负载，功率因数往往很低，常采取___的方法来提高电网的功率因数。
A. 并联电容
B. 串联电容
C. 串联电感
D. 并联电感
【单选题】
交流电压表及电流表指示的数值是___
A. 平均值
B. 有效值
C. 最大值
D. 瞬时值
【单选题】
RLC串联电路发生谐振，，R=10Ω，Ω，则谐振时的感抗为___
A. 10Ω
B. 40Ω
C. 20Ω
D. 30Ω
【单选题】
RL从电路获得最大功率，此时RL=___。
【单选题】
使用电解电容时___。
A. 负极接高电位，正极接低电位
B. 正极接高电位，负极接低电位
C. 正极接高电位，负极也可以接高电位
D. 不分正负极
【单选题】
开关接1时，电压表的读数为___。
A. 0V
B. 0.2V
C. 1.96V
D. 2V
【单选题】
开关接2时，电流表的电流为___。
A. 0A
B. 10A
C. 0.2A
D. 约等于0.2A
【单选题】
开关接1时，电流表中流过的短路电流为___。
A. 0A
B. 0.2A
C. 10A
D. 约等于0.2A
【单选题】
正弦交流电常用的表达方法有___。
A. 解析式表示法
B. 波形图表示法
C. 相量表示法
D. 以上都是
【单选题】
电感两端的电压相位超前电流___。
A. 90°
B. 180°
C. 360°
D. 30°
【单选题】
电容两端的电压相位滞后电流___。
A. 30°
B. 90°
C. 180°
D. 360°
【单选题】
应用戴维南定理求含源二端网络的输入等效电阻是将网络内各电动势___
【单选题】
LC 选频振荡电路，当电路频率等于谐振频率时，电路性质为___。
A. 电阻性
B. 感性
C. 容性
D. 纯电容性
【单选题】
阻值为4Ω的电阻和容抗为3Ω的电容串联，总复数阻抗为___
A. 3+j4
B. 3-j4
C. 4+j3
D. 4-j3
【单选题】
电动势为10V，内阻为2Ω的电压源变换成电流源时，电流源的电流和内阻是___
A. 10A，2Ω
B. 20A，2Ω
C. 5A，2Ω
D. 2A，5Ω
【单选题】
电流为5A，内阻为2Ω的电流源变换成一个电压源时，电压源的电动势和内阻为___
A. 10V，2Ω
B. 2.5V，2Ω
C. 0.4V，2Ω
D. 4V，2Ω
【单选题】
额定电压都为220V的40W、60W、100W三灯泡串联在220V的电源中，它们的发热量由大到小排列为___
A. 100W 60W 40W
B. 40W 60W 100W
C. 100W 40W 60W
D. 60W 100W 40W
【单选题】
在正弦交流电的解析式i=ImSin(ωt +φ)中，φ表示___
A. 频率
B. 相位
C. 初相位
D. 相位差
【单选题】
正弦交流电压u=100Sin(628t + 600)V，它的最大值为___。
A. 100 V
B. 100 V
C. 60V
D. 628 V
【单选题】
能表示容性电路电压与电流关系的相量图是___。
推荐试题
【填空题】
50.精确制导技术是指采用高技术直接命中概率超过___以上的武器。
【单选题】
What is an example of social engineering？___
A. gaining access to a computer by observing the user login credentials
B. gaining access to a build through an unguarded entrance
C. gaining access to a server by using a USB stick
D. gaining access to a server room by posing as local IT
【单选题】
Which type of Layer 2 attack enables the attacker to intercept traffic that is intended for one specific recipient？___
A. BPDU attack
B. DHCP starvation I LAB
C. MAC address spoofing
D. CAM table overflow
【单选题】
Which about nested policy maps in a zone-based firewall is true ?___
A. They are limited to two leve ls in a hierarchical policy
B. Parent policies are previously defined policies that are defined by using the service policy command
C. A child policy is a new policy that uses a pre-existing policy.
D. A child policy is a new that uses a pre-existing policy
【单选题】
In which configuration do you configure the ip ospf authentication key 1 command？___
A. routing process
B. interface
C. privileged
D. global
【单选题】
Which statement about command authorization and security contexts is true？___
A. If command authorization is configured， it must be enabled on all contexts.
B. The change to command invokes a new context session with the credentials of the currently
C. AAA settings are applied on a per-context basis
D. The enable. 15 user ang admins with chang to permission ha e dfferent command authorization levels pertontext
【单选题】
Which command do you enter to enable authentication for OSPF on an interface？___
A. router（config-if）#ip ospf message-digest-key 1 md5 CIS COPASS
B. router（config-if）#ip ospf authentication message-digest
C. router（config-if）#ip ospf authentication-key CISCOPASS
D. router（config-if）#area 0 authentication message-digest
【单选题】
What feature defines a campus area network？___
A. It has a single geographic location
B. It lacks external connectivity.
C. It has a limited number of segments.
D. It has limited or restricted Internet access
【单选题】
Which type of attack most commonly involves a direct attack on a network？___
A. :phishing
B. Trojan horse
C. denial of service
D. social engineering
【单选题】
What information does the key length provide in an encryption algorithm?___
A. the cipher block size
B. the hash bloc k size
C. the number of permutations
D. the packet size
【单选题】
How do you verify TaCACS+ connectivity to a device？___
A. You successfully log in to the device by using the local credentials
B. You connect via console port and receive the login prompt.
C. You connect to the device using SSH and receive the login prompt.
D. You successfully log in to the device by using ACS credentials
【单选题】
Which term best describes the concept of preventing the modification of data in transit and in storage？___
A. availability
B. confidentially
C. fidelity
D. integrity
【单选题】
Which loS command is used to define the authentication key for ntp？___
A. switch（config ）#ntp authentication-key 1 mds Clcs
B. switch（config ）#ntp authenticate
C. switch（config）#ntp trusted-key 1
D. switch（config）#ntp source 192.168.0.1
【单选题】
What is true about the cisco lOS Resilient Configuration feature ?___
A. The feature can be disabled through a remote session
B. There is additional space required to secure the primary cisco lOS image file.
C. The feature automatically detects image or configuration version mismatch.
D. Remote storage is used for securing files
【单选题】
When is the default deny all policy an exception in zone-based firewalls？___
A. when traffic terminates on the router via the self zone
B. when traffic traverses two interfaces in different zones
C. when traffic traverses two interfaces in the same zone
D. when traffic sources from the router via the self zone
【单选题】
.If an access port is assigned as an isolated port in a PVLAN， which network ports can it communicate with？___
A. promiscuous ports in the same PLVAN
B. isolated ports in the same PVLAN
C. all ports in the same PAVLAN at ILAR
D. all ports in the adjacent PVLAN
【单选题】
Which IPSEC mode is used to encypt traffic directly between a client and a server VPN endpoint？___
A. quick mode
B. transport mode
C. aggressive mode
D. tunnel mode
【单选题】
Which command do you enter to verify that a vpn connection is established between two endpoints and that the connection is passing traffic？ ___
A. Firewall#sh crypto session
B. Firewall#debug crypto isakmp
C. Firewall#tsh crypto ipsec sa
D. Firewall#sh crypto isakmp sa
【单选题】
which type of Pvlan port allows communication from all port types？___
A. isolated
B. in -line
C. community
D. promiscuous
【单选题】
Which command do you enter to configure your firewall to conceal internal addresses？___
A. no ip directed-broadcast
B. no ip logging facility
C. no proxy-arp
D. no ip inspect audit-trial
E. no ip inspect
F. route
【单选题】
Which feature defines a campus area network？ ___
A. It has a limited number of segments.
B. It has limited or restricted Internet access
C. It lacks ex1ternal connectivity.
D. It has a single geographic location
【单选题】
What technology can you use to provide data confidentiality data integrity and data origin authentication on your network？___
A. IPSec
B. Certificate Authority
C. IKE
D. Data
E. ncryption Standards
【单选题】
which standard is a hybrid protocol that uses oakley and skerne ke y exchanges is an ISAKMP framework？___
【单选题】
What is the actual los privilege level of User Exec mode？___
【单选题】
What is the effect of the asa command crypto isakmp nat-traversal？___
A. It opens port 500 only on the out side interface
B. It opens port 500 only on the inside interface
C. It opens port 4500 on all interfaces that are IPSec enabled
D. It opens port 4500 only on the out side interfac
【单选题】
Which Fire POWER preproce ssor engine is used to prevent SYN attacks？___
A. Inline normalization
B. IP Defragmentation
C. Ports can
D. etection
【单选题】
Which NAT type allows objects or groups to reference an IP address ？___
A. identity NAt
B. static NAT
C. dynamic
D. dynamic NAT
【单选题】
Which Auto NAT policies are processed first？___
A. Dynamic NAT with longest prefix
B. Dynamic NAT with shortest prefix
C. static NAT with longest prefix
D. static NAT with shortest prefix
【单选题】
Which feature allows a dynamic Pat pool to se lect the next address in the pat pool instead of the next port of an existing address？___
A. next IP
B. round robin
C. dynamic rotation
D. NAT address rotation
【单选题】
Which IPS detection method can you use to detect attacks that are based on the attackers IP address？___
A. anomally-based
B. policy-based
C. signature-based
D. reputation-based
【单选题】
Which type of encryption technology has the broadest platform support？___
A. software
B. middleware
C. file-level
D. hardware
【单选题】
Which type of address translation supports the initiation of comm unications bidirectionally ？___
A. multi-session PAT
B. dynamic NAT
C. dynamic PAT
D. static NAT
【单选题】
Which label is given to a person who uses existing computer scripts to hack into computers while lacking the expertise to write the own？___
A. script kiddy
B. white hat hacker
C. hacktivist
D. phreaker
【单选题】
What is the primary purpose of a defined rule in an IPS？___
A. to configure an event action that takes place when a signature is triggered
B. to define a set of actions that occur when a specific user logs in to the system
C. to configure an event action that is pre-defined by the system administrator
D. to detect internal attacks
【单选题】
Which option is the default valuce for the Diffie- Hell man group when configuring a site-to-site VPn on an asa device ？___
A. Group 1
B. Group 2
C. Group 5
D. Group 7
【单选题】
Which feature filters CoPP packets?___
A. access control lists
B. class maps
C. policy maps
D. route maps
【单选题】
Which command is used in global configuration mode to enable AAA？___
A. configure-model aaa
B. configure aaa-modelA
C. aaa new-model
D. aaa
E. XEC
【单选题】
Which statement about the given configuration is true？___
A. The single-connection command causes the device to establish one connection for all TACACS
B. The single-connection command causes the device to process one TacAcs request and then move to the next server
C. The timeout com mand causes the device to move to the next server after 20 seconds of TACACS inactive
【多选题】
What are two well-known security terms？___
A. phishing//网络钓鱼
B. ransomware //勒索软件
C. BPDU guard
D. LACP
E. hair-pinning
【多选题】
Which two commands must you enter to securely archive the primary bootset of a device___
A. router（config ）#secure boot-config
B. router（config）#auto secure
C. router（config）#secure boot-image
D. router（config）#service passw ord-encryption
